Fix linting errors across backend and frontend

Backend: auto-fix and format all ruff issues, manually fix B904/B023/
SIM117/B007/E741/F841 errors, suppress B008 (FastAPI Depends) and F821
(SQLAlchemy forward refs) in config. Frontend: allow constant exports,
disable React compiler-specific rules (set-state-in-effect,
preserve-manual-memoization).

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

backend/src/app/alembic/env.py

@@ -1,16 +1,14 @@
 import asyncio
 from logging.config import fileConfig
 
+from alembic import context
 from sqlalchemy import pool
 from sqlalchemy.ext.asyncio import async_engine_from_config
 
-from alembic import context
-
-from app.core.config import settings
-from app.core.database import Base, _get_async_url
-
 # Import all models so Base.metadata is populated
 import app.models  # noqa: F401
+from app.core.config import settings
+from app.core.database import Base, _get_async_url
 
 config = context.config