docs: richer report — data figures, success/failure frames, commit-pinned repo links

- experiment_charts.py generates 4 figures from experiments/ artifacts:
  held-out per-film F1, 16-combo ranking, DE search landscape, and the
  Downton detector-vs-tracker ghost timeline (replaces the blank
  title-card screenshot)
- new frames: 19-correct wedding shot (success case), Many Saints
  ghost-vs-unknown frame (three error classes in one image)
- rename rep4-optimizer-results.md -> model-bakeoff.md; rep4 kept only
  as the on-disk artifact prefix, explained once
- repo file references are now links via https://REPOLINK/<path>
  placeholders; build_site.sh pins them to the HEAD commit's raw URLs
  and fails the build if a linked path doesn't exist at HEAD
- drop references to removed scripts (scene_score.py, score_config.py)
  and to session-memory names; mark artifact-registry paths with their
  pull commands
- commit readme_example.jpg + pipeline_topology.svg so README renders
  on the plain Gitea repo view
- deploy_pages.sh: push built site/ to the gitea-pages branch

scripts/optimizer/dump_scene_montage.py

@@ -11,7 +11,7 @@ every currently-active TPI/FPI actor who has a REAL detection backing them, plus
 black caption panel below with two columns — Onscreen (has a real detection) and
 Offscreen (no real detection: FN misses, and "ghost" detections where the tracker
 is re-emitting a frozen last-known bbox with nothing there — see
-docs/rep4-optimizer-results.md) — names colour-coded by bucket, with a legend.
+docs/model-bakeoff.md) — names colour-coded by bucket, with a legend.
 
 A predicted bbox is checked against the dump's OWN raw per-frame face detections
 (IoU) to tell a real detection from a ghost. Ghosts are NEVER drawn as boxes (they