docs(templates): keep 3D smoke bridge read-only

[wh000wh000]

结论

threed_basic verification must measure the playable route, not a shipped debug backdoor. This change freezes the existing window.__opengame3d probe as read-only and requires keyboard/mouse/DOM evidence.

Production evidence

The one-POST v1.3 game aurora-island-treasure-3d-v1-3 is genuinely playable: an independent keyboard/mouse route collected 6/6 and reached the completion screen without calling teleport. Its generated self-test nevertheless added teleport, setRemaining, and mutable state to the public bridge, creating a path for future false-positive acceptance.

Change

Path	Contract added
agent-test/docs/modules/threed_basic/template_api.md	Exact bridge shape: isPaused + renderer only; no state mutation helpers
agent-test/docs/modules/threed_basic/threed_basic.md	Manual acceptance must use real keyboard/mouse input and visible DOM

The complementary L-layer control lives in non-Git opengame-server: check_generated_code.py --fail-bridge rejects extra runtime bridge keys for three.js games. It is intentionally not duplicated in this frozen repository.

Verification

Gate	Result
git diff --check	PASS
L-layer unit checks	PASS: readonly fixture accepted; teleport fixture rejected
Negative production sample	PASS: v1.3 is rejected with G4 keys setRemaining/state/teleport
Existing 3D sample	PASS: Crystal v1.2 bridge and full v2-accept
Existing Phaser sample	PASS: no new FAIL

Risk and rollback

Documentation-only frozen-layer change; runtime code and 2D routes are untouched. Revert commit b49c27f to restore prior guidance. Upstream dependencies remain PRs leigest519#47-leigest519#49.