feat(demo): add pipeline visualization demo mode

- Add --pipeline-demo flag for ASCII pipeline animation
- Create engine/pipeline_viz.py with animated pipeline graphics
- Shows data flow, camera modes, FPS counter
- Run with: python mainline.py --pipeline-demo --display pygame

mise.toml

@@ -40,6 +40,7 @@ run-both = { run = "uv run mainline.py --display both", depends = ["sync-all"] }
 run-client = { run = "mise run run-both & sleep 2 && $(open http://localhost:8766 2>/dev/null || xdg-open http://localhost:8766 2>/dev/null || echo 'Open http://localhost:8766 manually'); wait", depends = ["sync-all"] }
 run-demo = { run = "uv run mainline.py --demo --display pygame", depends = ["sync-all"] }
 run-pipeline = "uv run mainline.py --pipeline-diagram"
+run-pipeline-demo = { run = "uv run mainline.py --pipeline-demo --display pygame", depends = ["sync-all"] }
 
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 # Command & Control