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, 1 insertions, 3 deletions

diff --git a/packages/meshbay-node/tests/test_roster_pairing.py b/packages/meshbay-node/tests/test_roster_pairing.py
index 2e8c183..67c3b08 100644
--- a/packages/meshbay-node/tests/test_roster_pairing.py
+++ b/packages/meshbay-node/tests/test_roster_pairing.py
@@ -18,14 +18,13 @@ import pytest
 from cryptography.hazmat.primitives import serialization
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
 from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey
-
 from meshbay_common.crypto import generate_gek, pk_to_b64, unwrap_gek_aes
 from meshbay_common.join import ROLE_MEMBER, ROLE_OPERATOR, join_transcript
 from meshbay_node.indexer.group_index import GroupIndex
-from conftest import one_root
 from meshbay_node.roster import Roster, hash_code, normalize_code
 from meshbay_node.transport.webrtc_server import WebRTCPeerSession
 
+from conftest import one_root
 
 # ── Fixtures ──────────────────────────────────────────────────────────────────
 
@@ -694,7 +693,6 @@ async def test_unpinned_operator_loses_authority_immediately(tmp_path, roster):
 
 def _ui_client(tmp_path, roster, **extra):
     from fastapi.testclient import TestClient
-
     from meshbay_node.config import Config
     from meshbay_node.ui.app import create_ui_app