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, 20 insertions, 13 deletions

diff --git a/packages/meshbay-node/tests/test_webrtc_transport.py b/packages/meshbay-node/tests/test_webrtc_transport.py
index 0839d42..4aba99f 100644
--- a/packages/meshbay-node/tests/test_webrtc_transport.py
+++ b/packages/meshbay-node/tests/test_webrtc_transport.py
@@ -9,52 +9,59 @@ Uses local loopback (no STUN/ICE needed for localhost).
 
 import asyncio
 import base64
-from contextlib import asynccontextmanager
 import hashlib
 import hmac
 import os
 import struct
 import time
+from contextlib import asynccontextmanager
 
 import jwt
 import msgpack
 import pytest
+from aiortc import RTCPeerConnection, RTCSessionDescription
 from cryptography.hazmat.primitives import serialization
 from cryptography.hazmat.primitives.asymmetric.ed25519 import (
-    Ed25519PrivateKey, Ed25519PublicKey,
+    Ed25519PrivateKey,
+    Ed25519PublicKey,
 )
-from aiortc import RTCPeerConnection, RTCSessionDescription
-
 from meshbay_common import MNP_VERSION
 from meshbay_common.crypto import (
     generate_gek,
     pk_to_b64,
-    wrap_gek,
-    wrap_gek_aes,
     unwrap_gek,
     unwrap_gek_aes,
+    wrap_gek,
+    wrap_gek_aes,
 )
 from meshbay_common.groupbox import PURPOSE_ACK, PURPOSE_INDEX, unseal
-from meshbay_common.webcrypto import chunk_key_aes, decrypt_chunk_aes
 from meshbay_common.protocol import MNP
+from meshbay_common.webcrypto import chunk_key_aes, decrypt_chunk_aes
+
 TEST_GROUP = "g"
 
-from meshbay_common.handshake import (
-    NONCE_LEN, ROLE_CLIENT, ROLE_NODE, handshake_transcript,
-    make_proof, verify_proof, webrtc_binding,
-)
 from meshbay_common.adminop import (
     OP_FILE_DELETE,
     OP_INVITE_CREATE,
     admin_transcript,
 )
+from meshbay_common.handshake import (
+    NONCE_LEN,
+    ROLE_CLIENT,
+    ROLE_NODE,
+    handshake_transcript,
+    make_proof,
+    verify_proof,
+    webrtc_binding,
+)
 from meshbay_common.join import ROLE_MEMBER, ROLE_OPERATOR, join_transcript
 from meshbay_node.bundle_store import BundleStore
-from conftest import one_root
-from meshbay_node.roster import Roster
 from meshbay_node.indexer import DirectoryIndexer
+from meshbay_node.roster import Roster
 from meshbay_node.transport.webrtc_server import WebRTCTransport
 
+from conftest import one_root
+
 
 @pytest.fixture
 def sk_node():