Let the scene view hide symbols, names and shapes per asset kind

The scene view gets crowded once a scene holds many behaviors,
colliders and tilemaps. A new eye button in the topbar opens a list of
all placeable asset kinds, and each row has toggles for what the scene
view draws for that kind.

- The popup lists all 9 placeable kinds from Behavior to Tilemap, with
  the columns Symbol, Name and Shape. It stays open while switching.
- Sprite, Text and Tilemap draw no symbol, so their symbol toggle is
  greyed out. Their name toggle shows a new centred name tag, which is
  off by default.
- Shape exists for Collider and Tilemap. A hidden collider outline is
  neither drawn nor clickable. A hidden tilemap shape removes the
  collision outlines and the paint tint, the tiles stay visible.
- A hidden symbol takes no slot in the ring and draws no dashed link to
  its parent. A name that stays on moves to the centre of the object.
- The setting lives in the project as `sceneVisibility`, not in
  localStorage. Older projects load with the defaults, which match the
  view as it was.
- Switching has no undo step, like the game scale. It only changes the
  view. A change made during Play survives Stop.
- The rules sit in `src/core/model/sceneVisibility.ts`, the popup in
  `src/editor/panels/SceneVisibilityPopup.ts`. Four new SVG icons.

Not covered by a check: symbol off with name on for a kind with a
symbol, Text and Tilemap with names, and the paint tint with shape off.

Tests:
- ./check.sh: 173 files, 2515 tests, CHECK EXIT 0
- e2e 46: ALL PASSED, 17 checks. 46g clicks the popup, lays a small
  tilemap over the crate and removes it again.
- e2e 8 alone on a fresh seed: ALL PASSED, 23 checks. A red check in
  the partial run 2,8,46 came from the module selection.
- 8 new unit tests in tests/editor/scene-visibility.test.ts.
- 4 counter-probes, each fails its test: load ignores the saved value,
  Play skips the saved model, scene view ignores collider shape, scene
  view ignores tilemap shape.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

README.md

@@ -43,7 +43,7 @@ npm run build        # writes dist/ and regenerates index.html; the folder is wh
 The browser suite and the three example games need a machine with a GPU:
 
 ```bash
-node tools/seed-e2e.mjs && node tools/e2e.mjs      # the editor, 1418 checks (GM_STEPS=20 for one step)
+node tools/seed-e2e.mjs && node tools/e2e.mjs      # the editor, 1422 checks (GM_STEPS=20 for one step)
                                                    #   every tool signs in first – see the Accounts page
 node tools/seed-jumprun.mjs && node tools/smoke-jumprun.mjs
 node tools/seed-tetris.mjs && node tools/smoke-tetris.mjs