### Proposed Commit Message

Refactor Stats screen with enhanced data visualization and UI refinements

- **Stats Screen**:
    - Overhauls the "Listening Timeline" with specialized vertical and horizontal bar charts tailored to different time ranges (Day, Week, Month, Year, All).
    - Introduces `TimelineChartSpec` to manage layout logic, including dynamic item widths, scrolling thresholds, and label formatting for better density handling.
    - Implements a new `CategoryHorizontalBarChart` for top categories, featuring color palettes that dynamically match the selected dimension (Artist, Album, Genre, Song).
    - Replaces static "Listening timeline" text with dynamic supporting copy that explains data grouping per time range.
    - Enhances card visuals using container-specific color schemes and improved typography via custom variable fonts (`gflex_variable`, `genre_variable`).
    - Optimizes list performance by switching from manual horizontal scrolling to `LazyRow` for timeline entries.
- **UI/UX Refinements**:
    - Adds a `showTabIndicator` toggle to `LibraryScreen` and `EqualizerScreen` to selectively hide tab row indicators for a cleaner look.
    - Refines `StatsTimeRange` selector to support conditional indicators and improved spacing.
    - Updates `HighlightRow` and category badges with more consistent sizing and secondary metadata visibility.
- **Styling**:
    - Centralizes text styles for stats titles, axis labels, and metric values to ensure visual consistency across different chart types.
    - Refines color mappings for top artists and albums to use semantic container colors (secondary and tertiary).

…ng list UI

- **New Track Concentration Card**:
    - Introduces a "Track Concentration" section featuring a custom-drawn donut chart to visualize listening distribution across top tracks.
    - Adds detailed metrics for "Top 3 share", "Average plays per track", and total "Unique tracks" within the selected range.
    - Implements `TrackDistributionOverview` and helper components to display data slices with color-coded labels and percentages.
- **Enhanced Song List Visualization**:
    - Overhauls the "Tracks in this range" card with a more compact, structured layout using `Surface` containers for each entry.
    - Integrates `CategoryRankBadge` to highlight top-ranked songs with dynamic color schemes (Primary, Secondary, Tertiary).
    - Adds an explicit "Most played tracks" supporting description and replaces the simple text button with a full-width "Show all/Collapse" toggle.
    - Uses `animateContentSize` for smooth transitions when expanding or collapsing the song list.
- **UI & Styling Refinements**:
    - Updates several section titles to use `titleLargeEmphasized` for better visual hierarchy.
    - Simplifies background gradients in `StatsOverviewCard` and bar charts to solid colors or subtle transparencies for a cleaner look.
    - Adjusts spacing and padding across various stats cards to improve consistency and information density.
    - Updates `LinearProgressIndicator` styling with rounded caps and adjusted track heights.

… navigation gestures

- **Folder Management & SD Card Support**:
    - Introduces `FolderSource` to toggle between Internal Storage and SD Card.
    - Updates `MusicRepositoryImpl` to filter and build folder hierarchies based on the selected storage source.
    - Adds a storage source switcher within the library sorting bottom sheet.
    - Implements `StorageUtils` integration to detect available storage volumes and paths.
- **Enhanced Sorting**:
    - Expands folder sorting options to include song count (ascending/descending) and subfolder count (ascending/descending).
    - Persists folder sort preferences via `UserPreferencesRepository`.
    - Updates `LibraryStateHolder` and `LibraryScreen` to handle the new sorting logic and UI indicators.
- **Navigation & Gestures**:
    - Adds a "Behavior" settings category with a toggle for "Back gesture controls folders."
    - Implements `BackHandler` in `LibraryScreen` to allow the system back gesture to navigate up the folder hierarchy before exiting the tab.
    - Refactors `Breadcrumbs` to support dynamic root paths and labels based on the active storage source.
- **UI & View Models**:
    - Updates `PlayerUiState` and `SettingsViewModel` to track folder source, root paths, and gesture preferences.
    - Refines `LibrarySortBottomSheet` to support optional source-toggle content.
    - Improves folder path normalization and hierarchy resolution to ensure consistent behavior across different storage types.

- **Library & Navigation**:
    - Introduces a "Locate" action that allows users to quickly scroll to the currently playing song within the Songs, Liked, and Folders tabs.
    - Implements state management to track the visibility and action callbacks for the locate button independently for different library tabs.
    - Adds logic to monitor list scroll position using `snapshotFlow`, dynamically showing or hiding the locate button based on whether the current song is already visible on screen.
- **UI Components**:
    - Updates `LibraryActionRow` to include a new `MyLocation` icon button next to the sort button.
    - Adds smooth animations (slide and fade) for the locate button's appearance.
    - Refines the shape of action buttons using `animateDpAsState` to create a cohesive grouped appearance when the locate button is visible.
- **Tab Implementations**:
    - Updates `LibrarySongsTab`, `LibraryLikedSongsTab`, and `LibraryFolderDetail` to support current song location tracking and scroll-to-item functionality.
    - Integrates `DisposableEffect` to clean up visibility and action states when tabs are disposed or navigated away from.

- **Sync Management**:
    - Refactors `SyncManager.sync()` to be lifecycle-aware using `sharingScope`, implementing a check against the last sync timestamp.
    - Increases the minimum sync interval from 5 minutes to 6 hours (`MIN_SYNC_INTERVAL_MS`) to reduce redundant background work.
    - Removes the forced `mediaStoreObserver` rescan and the `onResume` sync trigger in `MainActivity` to prevent excessive syncing.
- **MainViewModel**:
    - Introduces `hasCompletedInitialSync` StateFlow to track if the library has ever been successfully synchronized.
    - Updates `isSyncing` and `isLibraryEmpty` initial states to `false` for more predictable UI behavior on startup.
- **UI & Performance**:
    - Refines the loading screen logic in `MainActivity` to only show the splash/loading state if the library is empty and an initial sync has never been completed.
    - Cleans up unused `SyncManager` injection in `MainActivity`.