fix(security): close MEDIUM ASVS findings — JWT pinning, SSE tickets, SSRF, mTLS pin, rate limits + correctness bugs

Auth (V2.1.1/V3.1.2, V2.1.3, V3.1.1):
- Pin JWT iss/aud/typ at mint and require+verify them at decode; revocation
  (jti denylist + tokens_valid_from) still enforced.
- Change-password now requires min_length=12.
- SSE auth moves off JWT-in-URL to a single-use 60s opaque ticket
  (POST /auth/sse-ticket); raw JWT in query no longer authenticates a stream.
  Removed dead fail-open get_stream_user helper.

Egress (V5.1.1, V9.1.1/V14.1.3):
- Webhook delivery + CRUD reject SSRF destinations (private/loopback/link-local/
  metadata, IPv4-mapped, multi-A-record) via resolved-IP validation, pin to the
  vetted IP, and never auto-follow redirects. Opt-out via DECNET_WEBHOOK_ALLOW_PRIVATE.
- UpdaterClient pins the worker leaf cert SHA-256 against the stored per-host
  fingerprint (fail closed on missing/mismatch); DECNET_VERIFY_HOSTNAME now
  defaults True.

Hardening (V13.1.3, V4.1.4, V13.1.2):
- Rate-limit change-password (5/min), enroll-bundle (10/min), webhook-create
  (20/min), host-delete (20/min) via the existing slowapi limiter.
- Correct false 'global auth middleware' comment; document enroll-bundle proxy
  trust.

Correctness (BUG-7..11):
- BUG-7 unbound bus in finally; BUG-8 apply_ceiling clamps to min(base,ceiling);
  BUG-9 commit before emit; BUG-10 multi-actor rearm for sub-threshold identities;
  BUG-11 normalize naive timestamps to UTC.

Already-closed (no change): V14.1.1, V2.1.2/V3.1.3, V5.1.2. Tests added for
every fix; unanimous adversarial review.

tests/api/swarm_mgmt/test_enroll_bundle.py

@@ -379,3 +379,31 @@ async def test_host_row_persisted_after_enroll(client, auth_token):
     assert row is not None
     assert row["name"] == "eta"
     assert row["status"] == "enrolled"
+
+
+# ─── Rate-limit enforcement ─────────────────────────────────────────────────
+
+
+@pytest.mark.anyio
+async def test_enroll_bundle_rate_limit_trips_after_10(client, auth_token):
+    """10 enroll-bundle POSTs from one IP → 11th returns 429.
+
+    Each request uses a unique agent name (otherwise the 2nd hits the 409
+    duplicate-name guard before the rate check fires).  The limiter is
+    10/minute for this endpoint.
+    """
+    for i in range(10):
+        r = await _post(client, auth_token, agent_name=f"rl-node-{i}")
+        # 201 (created) or 429 if limiter fires early — accept both.
+        assert r.status_code in (201, 429), f"attempt {i}: got {r.status_code}"
+
+    r = await _post(client, auth_token, agent_name="rl-node-overflow")
+    assert r.status_code == 429
+
+
+@pytest.mark.anyio
+async def test_enroll_bundle_route_has_rate_limit_decorator() -> None:
+    """Contract test: create_enroll_bundle must be wrapped by slowapi."""
+    from decnet.web.router.swarm_mgmt import api_enroll_bundle as _mod
+
+    assert getattr(_mod.create_enroll_bundle, "__wrapped__", None) is not None