Add Fix My Playlist feature

New endpoint POST /api/playlists/{id}/fix that analyzes a playlist
using Claude AI to identify outlier tracks that don't match the
overall vibe, and suggests better-fitting replacements.

Frontend shows results with warm amber cards for outliers and green
cards for replacements, with dismissible suggestions and visual
highlighting of flagged tracks in the track list.

backend/app/main.py

@@ -2,7 +2,7 @@ from fastapi import FastAPI
 from fastapi.middleware.cors import CORSMiddleware
 
 from app.core.config import settings
-from app.api.endpoints import auth, bandcamp, billing, lastfm, manual_import, playlists, profile, recommendations, youtube_music
+from app.api.endpoints import auth, bandcamp, billing, lastfm, manual_import, playlist_fix, playlists, profile, recommendations, youtube_music
 
 app = FastAPI(title="Vynl API", version="1.0.0", redirect_slashes=False)
 
@@ -17,6 +17,7 @@ app.add_middleware(
 app.include_router(auth.router, prefix="/api")
 app.include_router(billing.router, prefix="/api")
 app.include_router(playlists.router, prefix="/api")
+app.include_router(playlist_fix.router, prefix="/api")
 app.include_router(recommendations.router, prefix="/api")
 app.include_router(youtube_music.router, prefix="/api")
 app.include_router(manual_import.router, prefix="/api")