[AZ-180] Fix pre-existing test failures: patch JWT_SECRET in auth-dependent tests

Tests expecting file storage (image/video write) failed because JWT_SECRET was
not set in the test environment, causing require_auth to return "" (falsy),
skipping the storage block. Both tests now patch main.JWT_SECRET and use a
properly signed JWT.

Made-with: Cursor

tests/test_az178_streaming_video.py

@@ -1,6 +1,4 @@
 import asyncio
-import base64
-import json
 import os
 import tempfile
 import threading
@@ -275,20 +273,16 @@ class TestMediaContentHashFromFile:
         os.unlink(path)
 
 
+_TEST_JWT_SECRET = "az-test-secret-for-unit-tests-only-32b"
+
+
 def _access_jwt(sub: str = "u1") -> str:
     import jwt as pyjwt
-    secret = os.environ.get("JWT_SECRET", "")
-    if secret:
-        return pyjwt.encode(
-            {"exp": int(time.time()) + 3600, "sub": sub},
-            secret,
-            algorithm="HS256",
-        )
-    raw = json.dumps(
-        {"exp": int(time.time()) + 3600, "sub": sub}, separators=(",", ":")
-    ).encode()
-    payload = base64.urlsafe_b64encode(raw).decode().rstrip("=")
-    return f"h.{payload}.s"
+    return pyjwt.encode(
+        {"exp": int(time.time()) + 3600, "sub": sub},
+        _TEST_JWT_SECRET,
+        algorithm="HS256",
+    )
 
 
 class _FakeInfStream:
@@ -337,6 +331,7 @@ class TestDetectVideoEndpoint:
             from fastapi.testclient import TestClient
             client = TestClient(main.app)
             with (
+                patch.object(main, "JWT_SECRET", _TEST_JWT_SECRET),
                 patch.object(main, "get_inference", return_value=_FakeInfStream()),
                 patch.object(main.http_requests, "post", mock_post),
                 patch.object(main.http_requests, "put", mock_put),