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/login_throttle.py b/packages/meshbay-hub/src/meshbay_hub/login_throttle.py
index 3281088..bfd142e 100644
--- a/packages/meshbay-hub/src/meshbay_hub/login_throttle.py
+++ b/packages/meshbay-hub/src/meshbay_hub/login_throttle.py
@@ -24,7 +24,7 @@ locks somebody else's name from signing them out (§13.5b, AV26).
 """
 
 import hashlib
-from datetime import datetime, timedelta, timezone
+from datetime import UTC, datetime, timedelta
 
 from sqlalchemy import case, delete, select, update
 from sqlalchemy.ext.asyncio import AsyncSession
@@ -39,7 +39,7 @@ def _key(username: str) -> str:
 
 def _aware(dt: datetime) -> datetime:
     # SQLite hands back naive datetimes for a timezone-aware column.
-    return dt if dt.tzinfo is not None else dt.replace(tzinfo=timezone.utc)
+    return dt if dt.tzinfo is not None else dt.replace(tzinfo=UTC)
 
 
 def _insert_for(db: AsyncSession):
@@ -64,7 +64,7 @@ async def reserve(db: AsyncSession, username: str) -> tuple[bool, int]:
     if max_failures == 0:
         return True, 0
 
-    now = datetime.now(timezone.utc)
+    now = datetime.now(UTC)
     window = timedelta(minutes=limits["lockout_minutes"])
     window_start = now - window
     key = _key(username)
@@ -102,7 +102,7 @@ async def locked_for(db: AsyncSession, username: str) -> int:
         return 0
     remaining = (_aware(row.last_failure_at)
                  + timedelta(minutes=limits["lockout_minutes"])
-                 - datetime.now(timezone.utc)).total_seconds()
+                 - datetime.now(UTC)).total_seconds()
     return max(0, int(remaining + 0.999))
 
 
@@ -136,7 +136,7 @@ async def clear(db: AsyncSession, username: str) -> None:
 async def purge_expired(db: AsyncSession) -> int:
     """Rows whose failures have aged out. Every unknown name typed creates one."""
     limits = await hub_settings.login_limits(db)
-    cutoff = datetime.now(timezone.utc) - timedelta(minutes=limits["lockout_minutes"])
+    cutoff = datetime.now(UTC) - timedelta(minutes=limits["lockout_minutes"])
     result = await db.execute(
         delete(LoginThrottle).where(LoginThrottle.last_failure_at < cutoff))
     await db.commit()