[AZ-178] Add real-video streaming test, update e2e tests, mark task done

- Add tests/test_az178_realvideo_streaming.py: integration test that validates
  frame decoding begins while upload is still in progress using a real video fixture
- Add conftest.py: pytest plugin for per-test duration reporting
- Update e2e tests (async_sse, performance, security, streaming_video_upload, video)
  and run-tests.sh for updated test suite
- Move AZ-178 task to done/; add data/ to .gitignore (StreamingBuffer temp files)
- Update autopilot state to step 12 (Security Audit) for new feature cycle

Made-with: Cursor

_docs/_autopilot_state.md

@@ -2,8 +2,15 @@
 
 ## Current Step
 flow: existing-code
-step: 13
-name: Performance Test
+step: 12
+name: Security Audit
 status: not_started
 sub_step: 0
 retry_count: 0
+
+## Cycle Notes
+Previous full cycle (steps 1–14) completed. New cycle started for AZ-178.
+step: 8 (New Task) — DONE (AZ-178 defined)
+step: 9 (Implement) — DONE (implementation_report_streaming_video.md, 67/67 tests pass)
+step: 10 (Run Tests) — DONE (67 passed, 0 failed)
+step: 11 (Update Docs) — DONE (docs updated during step 9 implementation)