ops: add persistent GraphQL backend service

ops/project2/backend/README.md

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+# Project 2 GraphQL service
+
+These files document the persistent GraphQL service on the T07 VM. They do not
+contain database credentials and are not executed directly from a repository
+checkout. An administrator installs reviewed, root-owned copies.
+
+The deployment service uses the existing read-only repository mirror and
+`t07p2deploy` account. It checks out `origin/main`, runs the backend typecheck,
+tests and build, installs production dependencies in a commit-specific release
+directory, and atomically updates the backend `current` symlink. It does not
+run migrations or read the database credential.
+
+The API runs separately as `t07p2api`. Only this account can read
+`/etc/t07-project2-api/backend.env`. It listens on `127.0.0.1:3001`, so it is not
+exposed directly to the network. Apache proxies only
+`/project2/api/graphql` to the local API.
+
+Server-side paths:
+
+- `/etc/t07-project2-api/backend.env`: root-owned runtime configuration
+- `/var/lib/t07-project2/backend/releases/<commit>`: verified API releases
+- `/var/lib/t07-project2/backend/current`: selected API release
+- `/var/lib/t07-project2/backend/previous`: previous API release
+- `/usr/local/sbin/t07-project2-backend-deploy`: root-owned deployment script
+- `/etc/systemd/system/t07-project2-api.service`: persistent API service
+
+The installer creates the service account and installs root-owned copies, but
+does not create the secret environment file or start the API:
+
+```bash
+sudo /usr/bin/bash ops/project2/backend/install.sh
+```
+
+An administrator then installs `/etc/t07-project2-api/backend.env` from a private
+source with owner `root`, group `t07p2api` and mode `0640`. After #53 or its
+equivalent has reached `main`, prepare the release and start the service:
+
+```bash
+sudo systemctl start t07-project2-backend-deploy.service
+sudo systemctl enable --now t07-project2-api.service
+```
+
+Verify locally on the VM before testing through Apache:
+
+```bash
+curl --fail --silent --show-error \
+  --header 'content-type: application/json' \
+  --data '{"query":"{ health databaseStatus }"}' \
+  http://127.0.0.1:3001/
+```
+
+Then verify the public same-origin path:
+
+```bash
+curl --fail --silent --show-error \
+  --header 'content-type: application/json' \
+  --data '{"query":"{ venues(limit: 1) { totalCount items { id name } } }"}' \
+  http://localhost/project2/api/graphql
+```

ops/project2/backend/apache.conf

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+ProxyPass /project2/api/graphql http://127.0.0.1:3001/
+ProxyPassReverse /project2/api/graphql http://127.0.0.1:3001/

ops/project2/backend/backend.env.example

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+# Install the real file as /etc/t07-project2-api/backend.env with mode 0640.
+# Never commit the real database password.
+DATABASE_URL=postgresql://tapfinder_app:REPLACE_WITH_PASSWORD@127.0.0.1:5432/tapfinder_dev
+HOST=127.0.0.1
+PORT=3001

ops/project2/backend/deploy.sh

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+#!/usr/bin/env bash
+
+set -euo pipefail
+
+readonly STATE_ROOT='/var/lib/t07-project2'
+readonly MIRROR_DIR="${STATE_ROOT}/repository.git"
+readonly BUILD_ROOT="${STATE_ROOT}/builds"
+readonly BACKEND_ROOT="${STATE_ROOT}/backend"
+readonly RELEASES_DIR="${BACKEND_ROOT}/releases"
+readonly CURRENT_LINK="${BACKEND_ROOT}/current"
+readonly PREVIOUS_LINK="${BACKEND_ROOT}/previous"
+readonly REMOTE_URL='git@git.ntnu.no:IT2810-H26/T07-Project-2.git'
+readonly NODE_ROOT='/opt/node-v26.8.1'
+
+exec 9>"${STATE_ROOT}/backend-deploy.lock"
+/usr/bin/flock -n 9 || {
+  echo 'A Project 2 backend deployment is already running.' >&2
+  exit 1
+}
+
+if [[ ! -d "${MIRROR_DIR}" ]]; then
+  /usr/bin/git clone --quiet --mirror "${REMOTE_URL}" "${MIRROR_DIR}"
+fi
+
+/usr/bin/git --git-dir="${MIRROR_DIR}" fetch --quiet --prune origin \
+  '+refs/heads/main:refs/remotes/origin/main'
+
+commit_sha=$(/usr/bin/git --git-dir="${MIRROR_DIR}" rev-parse \
+  --verify 'refs/remotes/origin/main^{commit}')
+
+if [[ ! "${commit_sha}" =~ ^[0-9a-f]{40}$ ]]; then
+  echo 'Could not resolve a valid origin/main commit.' >&2
+  exit 1
+fi
+
+release_dir="${RELEASES_DIR}/${commit_sha}"
+
+if [[ ! -f "${release_dir}/.release-complete" ]]; then
+  build_dir=$(/usr/bin/mktemp -d "${BUILD_ROOT}/backend.XXXXXXXX")
+  release_stage="${RELEASES_DIR}/.staging-${commit_sha}-$$"
+
+  cleanup() {
+    /usr/bin/rm -rf -- "${build_dir}" "${release_stage}"
+  }
+  trap cleanup EXIT
+
+  deploy_index="${build_dir}/.deploy-index"
+  GIT_INDEX_FILE="${deploy_index}" \
+    /usr/bin/git --git-dir="${MIRROR_DIR}" --work-tree="${build_dir}" \
+    read-tree "${commit_sha}"
+  GIT_INDEX_FILE="${deploy_index}" \
+    /usr/bin/git --git-dir="${MIRROR_DIR}" --work-tree="${build_dir}" \
+    checkout-index --all --force
+  /usr/bin/rm -f -- "${deploy_index}"
+
+  cd "${build_dir}/server"
+  "${NODE_ROOT}/bin/npm" ci
+  "${NODE_ROOT}/bin/npm" run typecheck
+  "${NODE_ROOT}/bin/npm" run test:data
+  "${NODE_ROOT}/bin/npm" run build
+
+  /usr/bin/mkdir "${release_stage}"
+  /usr/bin/cp -a dist package.json package-lock.json "${release_stage}/"
+
+  cd "${release_stage}"
+  "${NODE_ROOT}/bin/npm" ci --omit=dev --ignore-scripts
+  /usr/bin/printf '%s\n' "${commit_sha}" >.commit
+  /usr/bin/touch .release-complete
+  /usr/bin/mv "${release_stage}" "${release_dir}"
+fi
+
+old_release=$(/usr/bin/readlink -f "${CURRENT_LINK}" 2>/dev/null || true)
+
+if [[ -n "${old_release}" && "${old_release}" != "${release_dir}" ]]; then
+  previous_stage="${BACKEND_ROOT}/.previous-$$"
+  /usr/bin/ln -s "releases/${old_release##*/}" "${previous_stage}"
+  /usr/bin/mv -Tf "${previous_stage}" "${PREVIOUS_LINK}"
+fi
+
+current_stage="${BACKEND_ROOT}/.current-$$"
+/usr/bin/ln -s "releases/${commit_sha}" "${current_stage}"
+/usr/bin/mv -Tf "${current_stage}" "${CURRENT_LINK}"
+
+echo "Prepared backend origin/main at ${commit_sha}."

ops/project2/backend/install.sh

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+#!/usr/bin/env bash
+
+set -euo pipefail
+
+if [[ "${EUID}" -ne 0 ]]; then
+  echo 'Run this installer as root.' >&2
+  exit 1
+fi
+
+readonly SOURCE_DIR=$(/usr/bin/dirname "$0")
+
+if ! /usr/bin/getent passwd t07p2deploy >/dev/null; then
+  echo 'The existing t07p2deploy account is required.' >&2
+  exit 1
+fi
+
+if ! /usr/bin/getent passwd t07p2api >/dev/null; then
+  /usr/sbin/useradd --system --home-dir /nonexistent --shell /usr/sbin/nologin \
+    t07p2api
+fi
+
+/usr/bin/install -d -o t07p2deploy -g t07p2deploy -m 0755 \
+  /var/lib/t07-project2/backend \
+  /var/lib/t07-project2/backend/releases
+/usr/bin/install -d -o root -g t07p2api -m 0750 /etc/t07-project2-api
+
+# The API account may traverse the state root to read the selected release, but
+# cannot list it or access the root-owned credential directory under /etc.
+/usr/bin/chmod 0751 /var/lib/t07-project2
+
+/usr/bin/install -o root -g root -m 0755 \
+  "${SOURCE_DIR}/deploy.sh" \
+  /usr/local/sbin/t07-project2-backend-deploy
+/usr/bin/install -o root -g root -m 0644 \
+  "${SOURCE_DIR}/t07-project2-backend-deploy.service" \
+  /etc/systemd/system/t07-project2-backend-deploy.service
+/usr/bin/install -o root -g root -m 0644 \
+  "${SOURCE_DIR}/t07-project2-api.service" \
+  /etc/systemd/system/t07-project2-api.service
+/usr/bin/install -o root -g root -m 0644 \
+  "${SOURCE_DIR}/apache.conf" \
+  /etc/apache2/conf-available/t07-project2-api.conf
+
+/usr/sbin/a2enmod proxy proxy_http
+/usr/sbin/a2enconf t07-project2-api
+/usr/sbin/apache2ctl configtest
+/usr/bin/systemctl daemon-reload
+/usr/bin/systemctl reload apache2
+
+echo 'Project 2 backend files are installed but the API is not started.'
+echo 'Install /etc/t07-project2-api/backend.env before preparing and starting a release.'

ops/project2/backend/t07-project2-api.service

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+[Unit]
+Description=T07 Project 2 GraphQL API
+After=network-online.target postgresql.service
+Wants=network-online.target
+
+[Service]
+Type=simple
+User=t07p2api
+Group=t07p2api
+WorkingDirectory=/var/lib/t07-project2/backend/current
+EnvironmentFile=/etc/t07-project2-api/backend.env
+Environment=NODE_ENV=production
+Environment=PATH=/opt/node-v26.8.1/bin:/usr/bin:/bin
+ExecStart=/opt/node-v26.8.1/bin/node dist/index.js
+Restart=on-failure
+RestartSec=5s
+UMask=0027
+NoNewPrivileges=true
+PrivateDevices=true
+PrivateTmp=true
+ProtectClock=true
+ProtectControlGroups=true
+ProtectHome=true
+ProtectHostname=true
+ProtectKernelLogs=true
+ProtectKernelModules=true
+ProtectKernelTunables=true
+ProtectSystem=strict
+RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
+RestrictSUIDSGID=true
+CapabilityBoundingSet=
+
+[Install]
+WantedBy=multi-user.target

ops/project2/backend/t07-project2-backend-deploy.service

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+[Unit]
+Description=Prepare verified T07 Project 2 backend release
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=oneshot
+User=t07p2deploy
+Group=t07p2deploy
+Environment=HOME=/var/lib/t07-project2/home
+Environment=PATH=/opt/node-v26.8.1/bin:/usr/bin:/bin
+Environment=NPM_CONFIG_CACHE=/var/lib/t07-project2/npm-cache
+Environment="GIT_SSH_COMMAND=/usr/bin/ssh -i /etc/t07-project2/deploy_key -o IdentitiesOnly=yes -o StrictHostKeyChecking=yes -o UserKnownHostsFile=/etc/t07-project2/known_hosts"
+ExecStart=/usr/local/sbin/t07-project2-backend-deploy
+UMask=0022
+NoNewPrivileges=true
+PrivateDevices=true
+PrivateTmp=true
+ProtectClock=true
+ProtectControlGroups=true
+ProtectHome=true
+ProtectHostname=true
+ProtectKernelLogs=true
+ProtectKernelModules=true
+ProtectKernelTunables=true
+ProtectSystem=strict
+ReadWritePaths=/var/lib/t07-project2
+RestrictAddressFamilies=AF_UNIX AF_INET AF_INET6
+RestrictSUIDSGID=true
+CapabilityBoundingSet=