Add three-up evidence boards for El Capitan and Joke Shop

TODO.md

@@ -125,8 +125,12 @@ except the rebuilt assets themselves.
       navigation obstacles and readable storytelling clusters.
 - [ ] Camera height: decide 1.7 m gameplay framing vs the ~1.55 m concept frames using
       `camera-cinematography`, and record the decision instead of leaving the mismatch open.
-- [ ] Build the venue three-up boards (real photo | generated concept | current capture) and
-      attach them to `docs/hollywood-boulevard-map.md` and `docs/joke-shop-map.md`.
+- [x] Build the venue three-up boards (real photo | generated concept | current capture):
+      `tools/three_up.py compose` renders labelled strips into `docs/screens/boards/` (caption
+      sidecar per board, `rows` emits README rows). Boards committed: El Capitan day, El Capitan
+      night, Joke Shop day. Tests in `tools/test_three_up.py`.
+- [ ] Link each committed board from `docs/hollywood-boulevard-map.md` and
+      `docs/joke-shop-map.md`.
 - [ ] Use the generated concept lighting and palette as the target for the `lighting`/`lookdev`
       pass, and record the deviations that stay accepted.
 - [ ] After the pass, regenerate the venue captures and update README plus both venue documents.
@@ -173,8 +177,10 @@ and never ship a generated or downloaded image without provenance.
 - [ ] Generate one concept board per venue with `tools/scene_concepts.py generate` (palette, facade
       rhythm, lighting), keep raw output gitignored, commit only the selected board, and record the
       model, prompt and spend in the sidecar.
-- [ ] Build a three-up sheet per venue (real photo | generated concept | current build capture) and
-      use it as the reference for the character, prop and venue verdicts.
+- [x] Build a three-up sheet per venue (real photo | generated concept | current build capture) and
+      use it as the reference for the character, prop and venue verdicts. (Done for the venue
+      exteriors via `docs/screens/boards/`; character/prop verdicts still use the Blender
+      preview sheets.)
 - [ ] Apply the screenshot rule to every workstream: each accepted fix updates the relevant row in
       `README.md` plus the matching docs page (`docs/blender_previews/README.md`,
       `docs/screenshots/README.md`, `docs/3d-model-review.md` or the venue map doc).