feat: deterministic sync progress indicator + related housekeeping

[NateEaton]

Bookmark list (initial sync):

• Add BookmarkSyncProgress sealed interface (Idle / Running) to BookmarkRepository; emit Running(page, totalPages) after each page in performFullSync(), reset to Idle in finally block.
• Fix BookmarkRepositoryImpl binding in AppModule: add @singleton so the Worker and ViewModel share the same instance and progress state is visible across both.
• Expose syncFraction: StateFlow<Float?> from BookmarkListViewModel, mapped from syncProgress.
• Replace pull-to-refresh spinner on initial load with a deterministic LinearProgressIndicator below the TopAppBar; PullToRefreshBox spinner is now only shown for user-initiated refreshes.
• Auto-scroll list to top when initial sync completes via snapshotFlow on isInitialLoading → scrollToTopTrigger.

Highlights (initial sync / pull-to-refresh):

• Add indeterminate LinearProgressIndicator below TopAppBar for auto-syncs (guarded by isRefreshing && !isUserRefreshing && !isInitialLocalLoad).
• Add isUserRefreshing tracking to HighlightsViewModel: set on retry(), reset via init observer when sync state leaves Running. Wire into HighlightsUiState and PullToRefreshBox so the circular spinner only shows for user-initiated pulls.
• Remove inline CircularProgressIndicator from the empty-state body (replaced by top-bar LinearProgressIndicator).

Logging:

• Revert HttpLoggingInterceptor from BODY back to BASIC; full response bodies were excessive for large libraries and impacted app load time.

Housekeeping:

• Update CHANGELOG.md with entries for 0.11.0 through 0.13.0.
• Update docs/WORKFLOW.md: add CHANGELOG.md update step to release prep.
• Remove _notes/reader-top-bar-scroll-behavior-spec.md from git tracking (_notes/ is local-only per .gitignore).
• Add docs/specs/deterministic-sync-progress-indicator-spec.md.