feat: persist teams in MariaDB

backend/src/db/schema.sql

@@ -109,4 +109,42 @@ CREATE TABLE IF NOT EXISTS users (
     COLLATE ascii_general_ci
     NOT NULL,
   UNIQUE INDEX idx_users_username (username)
+);
+
+-- Saved teams created by users.
+CREATE TABLE IF NOT EXISTS saved_teams (
+  id INT NOT NULL AUTO_INCREMENT PRIMARY KEY,
+  user_id INT NOT NULL,
+  name VARCHAR(100) NOT NULL,
+  format VARCHAR(50) NOT NULL,
+  created_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP,
+  updated_at TIMESTAMP NOT NULL DEFAULT CURRENT_TIMESTAMP
+    ON UPDATE CURRENT_TIMESTAMP,
+
+  INDEX idx_saved_teams_user_id (user_id),
+
+  FOREIGN KEY (user_id)
+    REFERENCES users(id)
+    ON DELETE CASCADE
+);
+
+-- Pokémon belonging to saved teams, with their original order.
+CREATE TABLE IF NOT EXISTS saved_team_pokemon (
+  team_id INT NOT NULL,
+  pokemon_id VARCHAR(50) NOT NULL,
+  position TINYINT UNSIGNED NOT NULL,
+
+  PRIMARY KEY (team_id, pokemon_id),
+  UNIQUE KEY uq_saved_team_position (team_id, position),
+
+  CONSTRAINT chk_saved_team_position
+    CHECK (position BETWEEN 1 AND 12),
+
+  FOREIGN KEY (team_id)
+    REFERENCES saved_teams(id)
+    ON DELETE CASCADE,
+
+  FOREIGN KEY (pokemon_id)
+    REFERENCES pokemon(id)
+    ON DELETE RESTRICT
 );