Add paste-your-songs manual import feature

Users can now paste a list of songs as text to create a playlist without
needing any service integration. Supports multiple formats: "Artist - Title",
"Title by Artist", "Artist: Title", and numbered lists. Includes a live
song count preview in the modal and free tier playlist limit enforcement.

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, billing, playlists, recommendations, youtube_music
+from app.api.endpoints import auth, billing, lastfm, manual_import, playlists, recommendations, youtube_music
 
 app = FastAPI(title="Vynl API", version="1.0.0")
 
@@ -19,6 +19,8 @@ app.include_router(billing.router, prefix="/api")
 app.include_router(playlists.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")
+app.include_router(lastfm.router, prefix="/api")
 
 
 @app.get("/api/health")