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, 2 insertions, 2 deletions

diff --git a/packages/meshbay-hub/tests/test_password_reset.py b/packages/meshbay-hub/tests/test_password_reset.py
index 823807c..b07f77c 100644
--- a/packages/meshbay-hub/tests/test_password_reset.py
+++ b/packages/meshbay-hub/tests/test_password_reset.py
@@ -9,7 +9,7 @@ the recovery key and is not exercised here.
 
 import base64
 import time
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 
 import pytest
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
@@ -126,7 +126,7 @@ async def test_an_expired_code_is_refused(client, db_session):
         select(User.id).where(User.username == "carol_test"))).scalar_one()
     row = (await db_session.execute(select(EmailVerification).where(
         EmailVerification.user_id == uid))).scalars().one()
-    row.expires_at = datetime.now(timezone.utc) - timedelta(minutes=1)
+    row.expires_at = datetime.now(UTC) - timedelta(minutes=1)
     await db_session.commit()
 
     r = await client.post("/v1/users/password/reset", json={