New version db changes

[spathon]

Preparation for Next.js version

Summary by CodeRabbit

• New Features

  • Consolidated, idempotent database migration and README.
  • Orphaned file cleanup script and automatic media file cleanup when records are removed.
  • Title input sanitization and improved slug handling when publishing posts.

• Bug Fixes

  • Deleted-user handling shows “[deleted]” for orphaned comments.
  • Improved file path safety and thumbnail handling.

• Database & Performance

  • Schema updates with cascading referential behavior and added performance indexes.

• Changes

  • Rate-limiting / account lockout fields added.
  • Post slugs now optional; group descriptions required.