fix: migrations, auth, providers health check, E2E tests, remove neko-sama

- Add proper Alembic initial migration (0001_initial_schema.py)
- Migrate refresh tokens from JSON file to SQLite (RefreshTokenTable)
- Remove Neko-Sama provider entirely (redirects to Gupy, not a host)
- Fix provider health check always showing UNKNOWN
  - Run check_all_health() on startup
  - Fix POST /providers/health/check background task bug
  - Add HTMX refresh after manual health check trigger
- Fix anime search relevance scoring with MIN_RELEVANCE_THRESHOLD=0.5
- Replace bare 'except:' with 'except Exception:' across codebase
- Add Playwright E2E test suite (12 tests, auth setup, helpers)
- Fix toast container blocking clicks via pointer-events: none
- Remove obsolete Jest/Vite test files and config
- Clean up obsolete test_watchlist scripts
- Update sonarr model comment for active providers

app/models/auth.py

@@ -62,5 +62,24 @@ class UserInDB(User):
     """Schema for user stored in database (with hashed password)"""
     hashed_password: str
 
+
+class RefreshTokenTable(SQLModel, table=True):
+    """Database table for refresh tokens"""
+    __tablename__ = "refresh_tokens"
+
+    id: str = Field(
+        default_factory=lambda: str(uuid.uuid4()),
+        primary_key=True,
+        index=True,
+        nullable=False
+    )
+    token_id: str = Field(index=True, unique=True)
+    username: str = Field(index=True)
+    created_at: datetime = Field(default_factory=datetime.now)
+    expires_at: Optional[datetime] = None
+    revoked: bool = Field(default=False)
+    revoked_at: Optional[datetime] = None
+
+
 # Import WatchlistItemTable here to resolve SQLModel Relationship mappings
 from .watchlist import WatchlistItemTable