Fix linting issues with ruff --fix

Applied automatic fixes for 315 out of 597 linting errors:
- Remove unused imports (F401)
- Fix f-string without placeholders (F541)
- Split multiple imports (E401)
- Remove redundant import aliases

Remaining 272 errors are mostly style issues:
- 164 E701: Multiple statements on one line (colon)
- 70 E402: Module import not at top of file
- 13 F841: Unused variables
- Various other style warnings

Code functionality unchanged - all fixes are cosmetic improvements.

saidsurucu-yargi-mcp-f5fa007/starlette_app.py

@@ -13,7 +13,7 @@ import os
 from starlette.applications import Starlette
 from starlette.routing import Mount, Route
 from starlette.requests import Request
-from starlette.responses import JSONResponse, PlainTextResponse, RedirectResponse
+from starlette.responses import JSONResponse
 from starlette.middleware import Middleware
 from starlette.middleware.cors import CORSMiddleware
 from starlette.middleware.authentication import AuthenticationMiddleware