style: ruff's own fixes, mechanically applied

`ruff check .` had gone unrun long enough to report 568 errors, which is the
same as having no linter: the next real finding would have been invisible in the
noise. This is the 521 it fixes by itself, in 173 files, and nothing else — the
98 it cannot fix are the next commit.

What actually changed: import sorting (225), imports nobody used (87, none of
them a re-export — no `__init__.py` is touched, which was the one way this could
have broken an import elsewhere), `datetime.timezone.utc` to `datetime.UTC` (69)
and `asyncio.TimeoutError` to `TimeoutError` (18), both plain aliases on the 3.12
this project requires, `Optional[X]` to `X | None` (24), and f-strings with
nothing to interpolate (19).

Checked rather than assumed: every module in the three packages still imports,
and the suite is 2893 passed — the same count, test for test, as the merge
before it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

1 files changed, 5 insertions, 5 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/tasks/cleanup.py b/packages/meshbay-hub/src/meshbay_hub/tasks/cleanup.py
index 5c52387..429575f 100644
--- a/packages/meshbay-hub/src/meshbay_hub/tasks/cleanup.py
+++ b/packages/meshbay-hub/src/meshbay_hub/tasks/cleanup.py
@@ -2,7 +2,7 @@
 
 import asyncio
 import logging
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 
 from sqlalchemy import delete, select
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -16,7 +16,7 @@ CLEANUP_INTERVAL_HOURS = 24
 
 
 async def purge_old_ip_logs(db: AsyncSession, retention_days: int = RETENTION_DAYS) -> int:
-    cutoff = datetime.now(timezone.utc) - timedelta(days=retention_days)
+    cutoff = datetime.now(UTC) - timedelta(days=retention_days)
     result = await db.execute(delete(IPLog).where(IPLog.timestamp < cutoff))
     await db.commit()
     return result.rowcount
@@ -26,7 +26,7 @@ PENDING_USER_EXPIRY_DAYS = 7
 
 
 async def purge_expired_verifications(db: AsyncSession) -> int:
-    now = datetime.now(timezone.utc)
+    now = datetime.now(UTC)
     result = await db.execute(
         delete(EmailVerification).where(EmailVerification.expires_at < now))
     await db.commit()
@@ -35,7 +35,7 @@ async def purge_expired_verifications(db: AsyncSession) -> int:
 
 async def purge_stale_pending_users(db: AsyncSession,
                                      expiry_days: int = PENDING_USER_EXPIRY_DAYS) -> int:
-    cutoff = datetime.now(timezone.utc) - timedelta(days=expiry_days)
+    cutoff = datetime.now(UTC) - timedelta(days=expiry_days)
     result = await db.execute(
         delete(User).where(User.status == "pending", User.created_at < cutoff))
     await db.commit()
@@ -93,7 +93,7 @@ async def find_unhosted_groups(db: AsyncSession, grace_days: int = UNHOSTED_GRAC
     whole reason the column exists rather than a check against the live socket
     registry, which would delete every group during a hub restart.
     """
-    cutoff = datetime.now(timezone.utc) - timedelta(days=grace_days)
+    cutoff = datetime.now(UTC) - timedelta(days=grace_days)
     result = await db.execute(
         select(Group).where(Group.hosted_at.is_(None), Group.created_at < cutoff))
     return list(result.scalars().all())