docs: enhance CLAUDE.md with migration details and directory updates

- Updated the `/library/` section to clarify its purpose.
- Added a new `/migrations/` directory section detailing database migration files managed by Phinx.
- Included migration commands for running and checking migration status.
- Revised the initial schema and seed data references for clarity.
- Improved formatting for consistency throughout the document.

CLAUDE.md

@@ -22,7 +22,8 @@ TorrentPier is a BitTorrent tracker engine written in PHP, designed for hosting
 - `/bt/` - BitTorrent tracker functionality (announce.php, scrape.php)
 - `/styles/` - Templates, CSS, JS, images
 - `/internal_data/` - Cache, logs, compiled templates
-- `/install/` - Installation scripts and SQL schema
+- `/install/` - Installation scripts and configuration examples
+- `/migrations/` - Database migration files (Phinx)
 
 ## Entry Points & Key Files
 
@@ -97,10 +98,24 @@ The project uses **StyleCI** with PSR-2 preset for code style enforcement. Style
 
 ## Database & Schema
 
-- MySQL schema: `/install/sql/mysql.sql`
+- **Database migrations** managed via Phinx in `/migrations/` directory
+- Initial schema: `20250619000001_initial_schema.php`
+- Initial seed data: `20250619000002_seed_initial_data.php`
 - UTF-8 (utf8mb4) character set required
 - Multiple database alias support for different components
 
+### Migration Commands
+```bash
+# Run all pending migrations
+php vendor/bin/phinx migrate --configuration=phinx.php
+
+# Check migration status
+php vendor/bin/phinx status --configuration=phinx.php
+
+# Mark migrations as applied (for existing installations)
+php vendor/bin/phinx migrate --fake --configuration=phinx.php
+```
+
 ## Legacy Compatibility Strategy
 
 The codebase maintains 100% backward compatibility while introducing modern alternatives: