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, 7 deletions

diff --git a/poc/spike6_gek.py b/poc/spike6_gek.py
index 89ab06c..3595d6d 100644
--- a/poc/spike6_gek.py
+++ b/poc/spike6_gek.py
@@ -16,14 +16,20 @@ Validates the full GEK lifecycle:
 The hub stores opaque encrypted blobs — it never sees the GEK in cleartext.
 """
 
-import asyncio, httpx, base64, os, json, time
+import asyncio
+import base64
+import json
+import os
+import time
 from pathlib import Path
+
+import blake3
+import httpx
+from cryptography.hazmat.primitives import hashes, serialization
 from cryptography.hazmat.primitives.asymmetric.ed25519 import Ed25519PrivateKey
 from cryptography.hazmat.primitives.asymmetric.x25519 import X25519PrivateKey, X25519PublicKey
 from cryptography.hazmat.primitives.ciphers.aead import ChaCha20Poly1305
 from cryptography.hazmat.primitives.kdf.hkdf import HKDF
-from cryptography.hazmat.primitives import hashes, serialization
-import blake3
 
 HUB_URL    = "http://meshbay.org"
 STATE_FILE = Path("node_state.json")
@@ -218,7 +224,7 @@ async def main():
         wrap_ms = (time.perf_counter()-t0)*1000
         print(f"  {PASS} Wrapped in {wrap_ms:.2f}ms")
         print(f"         pk_eph  : {bundle_bob['pk_eph_b64'][:24]}...")
-        print(f"         (different from Alice's bundle — ephemeral key is unique)")
+        print("         (different from Alice's bundle — ephemeral key is unique)")
 
         r = await c.post(
             f"{HUB_URL}/v1/groups/{group_id}/members/bob_member/gek",
@@ -301,10 +307,10 @@ async def main():
             print(f"  {PASS} Wrong private key correctly rejected (AEAD auth failed)")
 
         print("\n" + "="*55)
-        print(f"Spike 6 COMPLETE — GEK distribution validated.")
+        print("Spike 6 COMPLETE — GEK distribution validated.")
         print(f"  wrap_gek    : {wrap_ms:.2f} ms")
         print(f"  unwrap_gek  : {unwrap_ms:.2f} ms")
-        print(f"  Hub role    : stores opaque bundle, never sees GEK in clear")
-        print(f"  Security    : wrong key rejected by AEAD authentication tag")
+        print("  Hub role    : stores opaque bundle, never sees GEK in clear")
+        print("  Security    : wrong key rejected by AEAD authentication tag")
 
 asyncio.run(main())