feat: add Source filter to library filtering system (#1131)

* feat: add Source filter to library filtering system

Add a new Source filter section to the library options panel that allows
users to filter their library manga by source (e.g. MangaDex, MangaSee).

- Add hasSource to LibraryOptions type and category metadata
- Add source filtering logic in useGetVisibleLibraryMangas
- Add Source section with three-state checkboxes in filter UI
- Show loading spinner while source list loads
- Include source filter in active filter indicator

Closes #1057

* refactor: address review feedback for source filter

- Remove skip option, let query always run
- Use uniqBy from lodash/fp for deduplication
- Remove loading spinner (data available quickly)
- Wrap source section in length check

* docs: add source filter to changelog

---------

Co-authored-by: Copilot <noreply@github.com>

src/features/metadata/Metadata.constants.ts

@@ -200,6 +200,9 @@ export const APP_METADATA: Record<
     hasStatus: {
         convert: convertToObject<LibraryOptions['hasStatus']>,
     },
+    hasSource: {
+        convert: convertToObject<LibraryOptions['hasSource']>,
+    },
     customThemes: {
         convert: convertToObject<MetadataThemeSettings['customThemes']>,
     },
@@ -440,6 +443,7 @@ export const GLOBAL_METADATA_KEYS: AppMetadataKeys[] = [
     'hasDuplicateChapters',
     'hasTrackerBinding',
     'hasStatus',
+    'hasSource',
     // sort
     'sortBy',
     'sortDesc',