PPR-25: Books page filters overhaul

[Eoic]

Ticket

https://trello.com/c/8DcxPUgX

Summary

• Rebuild library filtering around an immutable LibraryFilters model with composable multi-select metadata, organization, reading, rating, progress, and date filters.
• Add a draggable advanced-filter bottom sheet with draft previews, active-filter badges, responsive sizing, and root-level modal backdrops.
• Keep the Books chip row synchronized with advanced filters, sorting, favorites, and small-grid, large-grid, and list display modes.
• Add matching search, sorting, filtering, and view controls to Shelves.
• Reuse the Books page for shelf contents while preserving shelf-specific filter state and facet options, plus editable shelf metadata.
• Remove obsolete query-suggestion, legacy filter-sheet, child-shelf, and duplicate shelf-books implementations.
• Update the affected provider, model, page, and widget tests for the new APIs and UI behavior.

Testing

• flutter analyze --no-fatal-infos — no issues found.
• flutter test --reporter expanded — 973 passed, 9 skipped, 0 failed.
• git diff --check — clean.

UI evidence

Compatibility and migration

• No database migration is required.
• Filter and view state remains session-scoped.
• Shelf and topic filters use stable record IDs.
• Reading-status defaults now use unread; current persisted enum values continue through the PowerSync mapper.
• Legacy query parser utilities remain available but are no longer wired into library search.

Notes

• The shelf-page “Add to shelf” action remains intentionally nonfunctional for now.
• Advanced filters are exposed from the main Books search bar; shelf pages reuse the same filtering infrastructure with shelf-scoped options.

Checklist

• The branch, commits, and pull request title follow the repository conventions.
• The change is complete and limited to the ticket's scope.
• Relevant tests have been added or updated.
• Formatting, analysis, and tests pass.
• Documentation, UI evidence, and migration notes are included where relevant.
• No credentials, personal data, copyrighted fixtures, or unrelated generated files are included.
• The branch is up to date with its target branch.

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