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, 16 insertions, 10 deletions

diff --git a/poc/spike4_nat.py b/poc/spike4_nat.py
index 44bcdca..e34a4c4 100644
--- a/poc/spike4_nat.py
+++ b/poc/spike4_nat.py
@@ -12,9 +12,15 @@ Tests:
   E. Update hub endpoint_hint
 """
 
-import asyncio, socket, struct, os, json, httpx, time, subprocess
+import asyncio
+import json
+import os
+import socket
+import struct
 from pathlib import Path
 
+import httpx
+
 PASS = "✓"; FAIL = "✗"; SKIP = "–"
 
 LOCAL_PORT      = 19000
@@ -148,7 +154,7 @@ async def udp_hole_punch_test(local_port: int) -> tuple[bool, str|None, str|None
 
     try:
         await asyncio.wait_for(recv_event.wait(), timeout=8)
-    except asyncio.TimeoutError:
+    except TimeoutError:
         pass
     finally:
         transport.close()
@@ -192,7 +198,7 @@ async def main():
             print(f"  {FAIL} {nat_type}")
             print(f"       Cloudflare STUN : {stun_ip1}:{stun_port1}")
             print(f"       Google STUN     : {stun_ip2}:{stun_port2}")
-            print(f"       → Hole punching unreliable; TURN relay required")
+            print("       → Hole punching unreliable; TURN relay required")
     elif stun_ip1:
         nat_type = "Unknown (only one STUN server responded)"
         print(f"  {SKIP} {nat_type}")
@@ -202,7 +208,7 @@ async def main():
         print(f"  {FAIL} {nat_type}")
 
     # ── Phase C: Bidirectional UDP hole punching ───────────────────────────────
-    print(f"\n[ C ] Bidirectional UDP hole punch (node → meshbay.org → echo back)")
+    print("\n[ C ] Bidirectional UDP hole punch (node → meshbay.org → echo back)")
     print(f"  Starting UDP echo server on meshbay.org:{MESHBAY_ECHO_PORT} ...")
     udp_ok = False
     seen_ext_addr = None
@@ -234,7 +240,7 @@ async def main():
         print(f"  {FAIL} Error: {e}")
 
     # ── Phase D: UPnP ─────────────────────────────────────────────────────────
-    print(f"\n[ D ] UPnP port mapping")
+    print("\n[ D ] UPnP port mapping")
     upnp_ip, upnp_port = try_upnp(LOCAL_PORT)
     if upnp_ip:
         print(f"  {PASS} Mapped {upnp_ip}:{upnp_port}")
@@ -243,7 +249,7 @@ async def main():
         print(f"  {FAIL} UPnP not available on this router")
 
     # ── Phase E: Update hub ────────────────────────────────────────────────────
-    print(f"\n[ E ] Update endpoint_hint on hub")
+    print("\n[ E ] Update endpoint_hint on hub")
     if endpoint_hint and state.get("username"):
         async with httpx.AsyncClient(timeout=10) as client:
             r = await client.post(f"{HUB_URL}/v1/users/login", json={
@@ -270,10 +276,10 @@ async def main():
     print(f"  UPnP                : {PASS + ' works' if upnp_ip else FAIL + ' disabled'}")
     print(f"  endpoint_hint       : {endpoint_hint or 'none'}")
     if udp_ok:
-        print(f"\n  P2P UDP is functional. QUIC transport will work.")
-        print(f"  Spike 4 COMPLETE.")
+        print("\n  P2P UDP is functional. QUIC transport will work.")
+        print("  Spike 4 COMPLETE.")
     else:
-        print(f"\n  P2P blocked — TURN relay needed for this configuration.")
-        print(f"  Spike 4 COMPLETE (with finding: relay required).")
+        print("\n  P2P blocked — TURN relay needed for this configuration.")
+        print("  Spike 4 COMPLETE (with finding: relay required).")
 
 asyncio.run(main())