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/web/test_web_api.py

@@ -76,57 +76,6 @@ class TestGetCurrentUser:
             await get_current_user(request)
 
 
-# ── get_stream_user ───────────────────────────────────────────────────────────
-
-class TestGetStreamUser:
-    @pytest.mark.asyncio
-    async def test_bearer_header(self):
-        from decnet.web.dependencies import get_stream_user
-        token = create_access_token({"uuid": "stream-uuid"})
-        request = MagicMock()
-        request.headers = {"Authorization": f"Bearer {token}"}
-        result = await get_stream_user(request, token=None)
-        assert result == "stream-uuid"
-
-    @pytest.mark.asyncio
-    async def test_query_param_fallback(self):
-        from decnet.web.dependencies import get_stream_user
-        token = create_access_token({"uuid": "query-uuid"})
-        request = MagicMock()
-        request.headers = {}
-        result = await get_stream_user(request, token=token)
-        assert result == "query-uuid"
-
-    @pytest.mark.asyncio
-    async def test_no_token_raises(self):
-        from fastapi import HTTPException
-        from decnet.web.dependencies import get_stream_user
-        request = MagicMock()
-        request.headers = {}
-        with pytest.raises(HTTPException) as exc_info:
-            await get_stream_user(request, token=None)
-        assert exc_info.value.status_code == 401
-
-    @pytest.mark.asyncio
-    async def test_invalid_token_raises(self):
-        from fastapi import HTTPException
-        from decnet.web.dependencies import get_stream_user
-        request = MagicMock()
-        request.headers = {}
-        with pytest.raises(HTTPException):
-            await get_stream_user(request, token="bad-token")
-
-    @pytest.mark.asyncio
-    async def test_missing_uuid_raises(self):
-        from fastapi import HTTPException
-        from decnet.web.dependencies import get_stream_user
-        token = create_access_token({"sub": "no-uuid"})
-        request = MagicMock()
-        request.headers = {"Authorization": f"Bearer {token}"}
-        with pytest.raises(HTTPException):
-            await get_stream_user(request, token=None)
-
-
 # ── web/api.py lifespan ──────────────────────────────────────────────────────
 
 class TestLifespan: