feat: add homepage with multiple sections

[martakam]

This PR builds a real homepage with multiple sections. The book search page is moved from / to /books, while / becomes the new homepage.

Homepage contents:

• A hero section inviting to search for books
• A "surprise me" button that opens a random book
• A section with some statistics about our book database
• A "for you" section if you're logged in based on your favorite genres
• A section with top rated books with more than 10 000 reviews
• A small section with book genres
• A section outlining how Readr works
• If the user is not logged in, a section inviting to create an account or log in

Other changes:

• A minRatings filter was added to the searchBooks query so we can show top rated books that aren't obscure
• The BookCard now also shows the rating directly
• Footer is updated with new design and links
• There is a database index for top rated books so the search goes fast
• The backend script runs with tsx watch so we do not need to restart the backend manually when changes are made
• Tests have been updated

Feel free to skip reviewing any *.generated.* files as usual. This PR is not as big as it looks - approximately 2000 lines of code change is the pnpm lockfile and 1200 lines is bookkeeping for the SQL migration.
Still, this PR could probably have been split into a few smaller ones, so I hope you can forgive me for not doing that.

Some of the code in this pull request has been created with the assistance of AI.

Closes #87

[hestro]

This is very cool!!
I have tested the new functionality and it seems like everything is working.

I added a few small styling suggestions as comments.