Feat: Add post-tone-map mesh diagnostics with RGBA overlays

Color antialiased half-edges by ray outcome with configurable Catppuccin colors and default opacity 0.5.

Rasterize premultiplied RGBA8 overlays on the producer and composite in place after writing the clean image. Keep single-frame, movie, and replay output consistent.

Add overlay, CLI, and queue ownership regressions and document the final output architecture.

tests/test_camera_cli.py

@@ -476,7 +476,7 @@ with tempfile.TemporaryDirectory(prefix='gr-camera-cli-', dir='/tmp/opencode') a
                 '--observer-position', 0.3 * time, 0, 0,
                 '--observer-velocity', 0.3, 0, 0,
                 '--look-ra-deg', 0, '--look-dec-deg', 0,
-                '--lens-map-output', path, '--output', tmp / 'alcubierre.png')
+                '--lens-map-output', path, '--output', tmp / f'alcubierre.{ext}')
             assert struct.unpack_from('<d', path.read_bytes(),
                                       MAP_FRAME_HEADER_START + 8)[0] == time
             vertices, triangles = map_vertices(path)