Fix all 33 ruff linting errors causing CI failures

- Remove unused imports (F401) across 17 files
- Fix f-strings without placeholders (F541) in 3 files
- Add noqa: E712 to SQLAlchemy == True comparisons (valid ORM pattern)
- Preserve alembic side-effect import with noqa: F401

Co-authored-by: christianlouis <361235+christianlouis@users.noreply.github.com>
Agent-Logs-Url: https://github.com/christianlouis/pop_puller_to_gmail/sessions/99c3a25f-3479-473d-ac95-9faaa0ddd55b

backend/app/workers/tasks.py

@@ -5,7 +5,6 @@ Celery tasks for background email processing.
 import asyncio
 import os
 from datetime import datetime, timedelta
-from typing import List
 from celery import Task
 import logging
 
@@ -24,7 +23,6 @@ from app.services.mail_processor import MailProcessor
 from app.services.gmail_service import GmailService, GmailInjectionError
 from app.core.config import settings
 from sqlalchemy import select, and_
-from sqlalchemy.ext.asyncio import AsyncSession
 
 logger = logging.getLogger(__name__)
 
@@ -94,7 +92,7 @@ async def process_mail_account(account_id: int):
                 gmail_cred_result = await db.execute(
                     select(GmailCredential).where(
                         GmailCredential.user_id == account.user_id,
-                        GmailCredential.is_valid == True,
+                        GmailCredential.is_valid == True,  # noqa: E712
                     )
                 )
                 gmail_cred = gmail_cred_result.scalar_one_or_none()
@@ -222,7 +220,7 @@ async def process_all_enabled_accounts():
             result = await db.execute(
                 select(MailAccount).where(
                     and_(
-                        MailAccount.is_enabled == True,
+                        MailAccount.is_enabled == True,  # noqa: E712
                         MailAccount.status.in_(
                             [AccountStatus.ACTIVE, AccountStatus.TESTING]
                         ),