feat(web): finish RE 5000PBR lesson video and fix non-ASCII GLB import

- Add 11:07 Chinese-narrated lesson video, VTT, poster and 13 chapter screenshots.
- Regenerate 20-render WebGL2 matrix and 15 operation captures on RTX 4060.
- Fix WASM staging for non-ASCII import filenames (猴头.glb); rebuild web_engine.
- Harden lesson video recording pipeline; fix stale lesson-link E2E selector.
- Add RE PBR derived libraries, lesson page, evidence and status report.

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

.gitignore

@@ -33,3 +33,12 @@ mylog.txt
 .idea/
 .vscode/
 *.swp
+
+# RE 5000PBR lesson local artifacts
+/tools/web/.tts-venv/
+/tests/golden/_backup-*/
+/tests/golden/RE-PBR-VIDEO-001/narration/
+/tests/golden/RE-PBR-VIDEO-001/*.webm
+/tests/golden/RE-PBR-VIDEO-001/diagnostics/
+*.blend1
+*~