feat: add fuzzy tags_filter to search query

- Add tags_filter parameter to SearchMediaItemsUnified
- Add EXISTS clause with word_similarity() for fuzzy tag matching
- Add tag similarity scoring to ORDER BY clause (GREATEST function)
- Add SearchTagsValues query for autocomplete with ::TEXT cast
- Keep genre_filter for backward compatibility
- Regenerate Go code with sqlc generate

This enables filtering books by tags (from Calibre) instead of genre,
which is always NULL for imported books. Uses fuzzy matching consistent
with author/series filters, with best matches sorted first.

Relates to IMPLEMENTATION_TAGS_FILTER.md Phase 1

internal/database/querier.go

@@ -290,6 +290,7 @@ type Querier interface {
 	SearchMediaItems(ctx context.Context, arg SearchMediaItemsParams) ([]SearchMediaItemsRow, error)
 	SearchMediaItemsUnified(ctx context.Context, arg SearchMediaItemsUnifiedParams) ([]SearchMediaItemsUnifiedRow, error)
 	SearchSeriesValues(ctx context.Context, arg SearchSeriesValuesParams) ([]SearchSeriesValuesRow, error)
+	SearchTagsValues(ctx context.Context, arg SearchTagsValuesParams) ([]SearchTagsValuesRow, error)
 	// Library Visibility queries
 	SetLibraryVisibility(ctx context.Context, arg SetLibraryVisibilityParams) (LibraryVisibility, error)
 	// Set system config