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, 5 deletions

diff --git a/packages/meshbay-node/src/meshbay_node/transport/quic_client.py b/packages/meshbay-node/src/meshbay_node/transport/quic_client.py
index af87b70..273f225 100644
--- a/packages/meshbay-node/src/meshbay_node/transport/quic_client.py
+++ b/packages/meshbay-node/src/meshbay_node/transport/quic_client.py
@@ -13,18 +13,14 @@ import base64
 import logging
 import os
 import struct
-from pathlib import Path
 
-import jwt
 import msgpack
-from aioquic.asyncio import connect, QuicConnectionProtocol
+from aioquic.asyncio import QuicConnectionProtocol, connect
 from aioquic.quic.configuration import QuicConfiguration
 from aioquic.quic.events import QuicEvent, StreamDataReceived
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PublicKey
-
 from meshbay_common import MNP_VERSION
 from meshbay_common.groupbox import PURPOSE_ACK, PURPOSE_INDEX, unseal
-from meshbay_common.protocol import MNP, file_chunk_plaintext
 from meshbay_common.handshake import (
     MNP_MIN_SUPPORTED,
     NONCE_LEN,
@@ -36,6 +32,7 @@ from meshbay_common.handshake import (
     quic_binding,
     verify_proof,
 )
+from meshbay_common.protocol import MNP, file_chunk_plaintext
 
 
 def _peer_cert_der(proto) -> bytes | None: