fix(pipeline): probe duration via cv2 (no ffprobe dep); wire MASTER_MAX_W; fps-sync note

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/test_pipeline_integration.py

@@ -2,7 +2,7 @@ from pathlib import Path
 
 import pytest
 
-from tools.pipeline.run import process_clip, resolve_ffmpeg
+from tools.pipeline.run import probe_duration, process_clip, resolve_ffmpeg
 
 _FOREST = Path("simulator/sample_media/forest/base.mp4")
 
@@ -18,6 +18,14 @@ def _ffmpeg_available() -> bool:
 _HAS_FF = _ffmpeg_available()
 
 
+@pytest.mark.skipif(not _FOREST.exists(),
+                    reason="forest POC base absent (run simulator/setup_sample_media.py)")
+def test_probe_duration_reads_forest_base():
+    if not _FOREST.exists():
+        pytest.skip("forest POC base absent")
+    assert probe_duration(_FOREST) > 0
+
+
 @pytest.mark.skipif(not _HAS_FF,
                     reason="neither system ffmpeg nor imageio-ffmpeg available")
 @pytest.mark.skipif(not _FOREST.exists(),