scanner: fix library isolation, file mtime, force rescan, and deletion handling

Fix 1 - File modification time for created_at:
- Get file.ModTime() in processMediaFile and pass to CreateMediaItem
- Modified SQL INSERT to include created_at column

Fix 2 - Force rescan UPDATE instead of DELETE+INSERT:
- Changed force rescan logic to call updateMediaItem instead of delete + create
- Preserves created_at timestamp on force rescan

Fix 3 - GetMediaItemByFilePath filters by library_id:
- Added library_id to WHERE clause in SQL query
- Created GetMediaItemByFilePathAnyLibrary for cross-library lookups (KOReader)
- Added SetLibraryID method to MediaScanner
- Updated handler to call SetLibraryID for watch mode

Fix 4 - File deletion handling with persistent logging:
- Added fsnotify.Remove handler in WatchChanges
- Added orphan cleanup in ScanFolders after scan completes
- Created scanner_logger.go with daily log rotation (7 days)
- Logs to /app/logs/scanner-deletes-YYYY-MM-DD.log and scanner-errors-YYYY-MM-DD.log
- Individual deletes with enhanced safety logging

Note: Integration tests can now safely scan /app/uploads because
GetMediaItemByFilePath now filters by library_id, preventing
cross-library interference.

internal/database/queries/queries.sql

@@ -128,8 +128,8 @@ ORDER BY l.created_at DESC;
 
 -- Media Items queries
 -- name: CreateMediaItem :one
-INSERT INTO media_items (library_id, title, author, isbn, description, file_path, file_size, mime_type, cover_image_path, series, series_number, tags, tags_search, asin, date_published, publisher, contributors, contributors_search, language, edition, page_count, genre, copyright_year, goodreads_id, openlibrary_id, google_books_id, added_by_admin_id)
-VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18, $19, $20, $21, $22, $23, $24, $25, $26, $27)
+INSERT INTO media_items (library_id, title, author, isbn, description, file_path, file_size, mime_type, cover_image_path, series, series_number, tags, tags_search, asin, date_published, publisher, contributors, contributors_search, language, edition, page_count, genre, copyright_year, goodreads_id, openlibrary_id, google_books_id, added_by_admin_id, created_at)
+VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11, $12, $13, $14, $15, $16, $17, $18, $19, $20, $21, $22, $23, $24, $25, $26, $27, $28)
 RETURNING *;
 
 -- name: GetMediaItem :one
@@ -300,7 +300,10 @@ RETURNING *;
 DELETE FROM media_items WHERE id = $1;
 
 -- name: GetMediaItemByFilePath :one
-SELECT * FROM media_items WHERE file_path = $1;
+SELECT * FROM media_items WHERE file_path = $1 AND library_id = $2;
+
+-- name: GetMediaItemByFilePathAnyLibrary :one
+SELECT * FROM media_items WHERE file_path = $1 LIMIT 1;
 
 -- name: GetReadingProgress :one
 SELECT * FROM reading_progress WHERE media_item_id = $1 AND user_id = $2;