Adds tools/character_studio.py, a demo app over the character-profile endpoints:
extract a character from real photos/videos (POST /v1/characters/extract), review
and prune the reference crops, then generate a brand-new video starring that
person (POST /v1/video/generations with character_profiles + keyframe_identity).

CLI core plus a `web` subcommand serving the same pipeline in the browser. The
UI honours X-Forwarded-Prefix, so it works at the root or under a sub-path mount.
Every generated mp4 gets its request body written alongside it, so the demo also
doubles as a worked API example.

Wired in as a bundled tool like the other UIs: supervisord program on port 7791
(autostart via CODERAI_TOOL_CHARACTER_STUDIO, on by default), entrypoint env
defaults, run_oci.sh --enable/--disable-tool + --tool-arg names, nginx route at
/character/, service smoke test, and the run banner/README URLs.

Version bumped to 0.1.88 so the in-image upgrade path ships it.
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0182DhR1eFNPQyGmDrpHbedY