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, 13 insertions, 11 deletions

diff --git a/packages/meshbay-hub/src/meshbay_hub/mail.py b/packages/meshbay-hub/src/meshbay_hub/mail.py
index 126ed45..1eb7c51 100644
--- a/packages/meshbay-hub/src/meshbay_hub/mail.py
+++ b/packages/meshbay-hub/src/meshbay_hub/mail.py
@@ -16,7 +16,7 @@ import asyncio
 import hashlib
 import logging
 import smtplib
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 from email.message import EmailMessage
 
 log = logging.getLogger(__name__)
@@ -79,7 +79,7 @@ async def _take(db, key: str, window: timedelta, ceiling: int,
     """
     from meshbay_hub.db.models import MailQuota
 
-    now = datetime.now(timezone.utc)
+    now = datetime.now(UTC)
     row = await db.get(MailQuota, key)
     if row is None:
         row = MailQuota(key=key, window_start=now, count=0, last_sent=None)
@@ -87,14 +87,14 @@ async def _take(db, key: str, window: timedelta, ceiling: int,
 
     started = row.window_start
     if started.tzinfo is None:
-        started = started.replace(tzinfo=timezone.utc)
+        started = started.replace(tzinfo=UTC)
     if now - started >= window:
         row.window_start, row.count = now, 0
 
     if cooldown is not None and row.last_sent is not None:
         last = row.last_sent
         if last.tzinfo is None:
-            last = last.replace(tzinfo=timezone.utc)
+            last = last.replace(tzinfo=UTC)
         if now - last < cooldown:
             raise MailRefused("too soon since the last message to this recipient")
 
@@ -131,12 +131,12 @@ async def _announce_exhaustion(scope: str) -> None:
     try:
         async with get_session_factory()() as db:
             key = f"alert:{scope}"
-            now = datetime.now(timezone.utc)
+            now = datetime.now(UTC)
             row = await db.get(MailQuota, key)
             if row is not None and row.last_sent is not None:
                 last = row.last_sent
                 if last.tzinfo is None:
-                    last = last.replace(tzinfo=timezone.utc)
+                    last = last.replace(tzinfo=UTC)
                 if now - last < timedelta(hours=1):
                     return
             if row is None:
@@ -202,9 +202,10 @@ async def reserve(db, purpose: str, address: str) -> None:
 
 async def status(db) -> dict:
     """What the operator sees in the panel: is the hub still sending?"""
+    from sqlalchemy import func, select
+
     from meshbay_hub import hub_settings
     from meshbay_hub.db.models import MailQuota
-    from sqlalchemy import func, select
 
     limits = await hub_settings.mail_limits(db)
     row = await db.get(MailQuota, "hour")
@@ -213,8 +214,8 @@ async def status(db) -> dict:
     if row is not None:
         started = row.window_start
         if started.tzinfo is None:
-            started = started.replace(tzinfo=timezone.utc)
-        if datetime.now(timezone.utc) - started < timedelta(hours=1):
+            started = started.replace(tzinfo=UTC)
+        if datetime.now(UTC) - started < timedelta(hours=1):
             used, window_start = row.count, started.isoformat()
 
     recipients = await db.scalar(
@@ -244,10 +245,11 @@ async def status(db) -> dict:
 
 async def purge_expired_quota(db) -> int:
     """Drop counters whose window has passed. Returns how many went."""
-    from meshbay_hub.db.models import MailQuota
     from sqlalchemy import delete
 
-    cutoff = datetime.now(timezone.utc) - timedelta(days=1)
+    from meshbay_hub.db.models import MailQuota
+
+    cutoff = datetime.now(UTC) - timedelta(days=1)
     result = await db.execute(
         delete(MailQuota).where(MailQuota.window_start < cutoff))
     await db.commit()