Fix CI/CD pipeline and code quality issues

## Major Changes
- Fixed all TypeScript errors in web client for successful compilation
- Resolved 82+ Python lint errors across backend services
- Updated Flutter SDK compatibility for mobile app
- Fixed security workflow configuration

## Web Client Fixes
- Fixed import path in DragonflyDashboard.vue (dragonflyApi import)
- All TypeScript compilation now passes without errors

## Backend Lint Fixes
- Updated type annotations to modern Python syntax (dict instead of Dict, X | None instead of Optional[X])
- Replaced try-except-pass with contextlib.suppress(Exception)
- Removed unused imports (Dict, Optional, Any, Iterator, etc.)
- Fixed bare except clauses to use Exception
- Sorted and formatted imports with ruff
- Applied ruff format to 27 files

## Workflow Fixes
- Updated Flutter SDK constraint from ^3.10.4 to ^3.5.0 (compatible with Flutter 3.24.0)
- Changed pip-audit format from github to json in security.yml
- Added comprehensive CI workflows (readiness-gate.yml, security.yml)

## Infrastructure
- Added DragonflyDB caching system integration
- Enhanced Docker configuration with multi-stage builds
- Added pytest configuration and test infrastructure
- Improved production readiness with proper error handling

## Verification
- backend-lint job: ✅ Succeeded
- web job: ✅ Succeeded
- Ready for GitHub deployment

All CI/CD issues resolved. Codebase now passes all quality checks.

src/swingmusic/data/__init__.py

@@ -42,7 +42,6 @@ ARTIST_SPLIT_IGNORE_LIST = {
     "Hall & Oates",
     "Tom Petty & The Heartbreakers",
     "Sly & the Family Stone",
-    "Booker T. & the M.G.'s",
     "KC & the Sunshine Band",
     "Huey Lewis & the News",
     "Joan Jett & the Blackhearts",
@@ -63,7 +62,6 @@ ARTIST_SPLIT_IGNORE_LIST = {
     "Ashford & Simpson",
     "Sam & Dave",
     "Ike & Tina Turner",
-    "Sonny & Cher",
     "Captain & Tennille",
     "Hootie & the Blowfish",
     "Diana Ross & the Supremes",
@@ -77,5 +75,5 @@ ARTIST_SPLIT_IGNORE_LIST = {
     "Aly & AJ",
     "Maddie & Tae",
     "Nico & Vinz",
-    "Yusuf / Cat Stevens"
+    "Yusuf / Cat Stevens",
 }