feat(llm): add OrcaRouter as a named OpenAI-compatible gateway

[XiaoHuo888-hue]

Summary

Adds OrcaRouter as a named, OpenAI-compatible smart-routing gateway for FunClip's transcript-driven LLM clipping — mirroring the existing atlascloud/ and minimax/ gateway routes.

Users can now select any orcarouter/ model in the LLM Model Name dropdown (orcarouter/auto, orcarouter/fusion, orcarouter/fusion-flash, orcarouter/fusion-mini), paste an OrcaRouter API key in the APIKEY box, and run 'LLM Inference'. FunClip sends the transcript and prompts to https://api.orcarouter.ai/v1/chat/completions, and the returned segments work with the existing 'AI Clip' button unchanged.

• funclip/llm/openai_api.py: orcarouter/ prefix branch in _resolve_model_config() → ORCAROUTER_API_BASE (https://api.orcarouter.ai/v1, overridable via ORCAROUTER_API_BASE) + ORCAROUTER_API_KEY env fallback. Model IDs are sent verbatim with the orcarouter/ prefix, as the gateway routes by namespace.
• funclip/launch.py: SUPPORT_LLM_PREFIX + dispatch branch + 4 gateway model dropdown entries.
• tests/test_orcarouter_api.py, tests/test_orcarouter_launch_integration.py: unit tests mirroring the MiniMax/AtlasCloud conventions.
• README.md / README_zh.md: "Using OrcaRouter as your LLM gateway (optional)" section.

It also runs gateway-level, zero-trust security for AI agents on the same endpoint — screening every prompt/response and governing every tool call on a default-deny basis, with no application code changes.

User impact

FunClip users get a one-dropdown way to route LLM-assisted clipping through a single gateway that can switch routing targets (frontier and open-weight models) without touching FunClip configuration.

Validation

• I ran the relevant tests or commands:
  • python3 -m pytest -q tests/test_openai_api.py tests/test_minimax_api.py tests/test_minimax_launch_integration.py tests/test_orcarouter_api.py tests/test_orcarouter_launch_integration.py → 18 passed
  • python3 -m py_compile funclip/launch.py funclip/videoclipper.py funclip/utils/subtitle_utils.py funclip/llm/openai_api.py → OK
  • git diff --check → clean
  • Full suite: 6 pre-existing env failures (missing twelvelabs/gradio) identical on clean main; zero regressions.
• I checked the affected README/docs links, if changed.
• I verified the affected LLM path, if changed: L3 live test with a real key through the actual openai_call() code path → orcarouter/auto → https://api.orcarouter.ai/v1/chat/completions → 200 ORCA-LIVE-OK; _resolve_model_config("orcarouter/auto") resolves base_url https://api.orcarouter.ai/v1 and preserves the full model ID.

Screenshots or clips

No UI visuals — the change adds dropdown entries and a routing branch. The dropdown now lists orcarouter/auto, orcarouter/fusion, orcarouter/fusion-flash, orcarouter/fusion-mini.

Notes for reviewers

• OrcaRouter is a smart-routing gateway: model IDs must keep the orcarouter/ prefix (a bare auto is not routable), so unlike AtlasCloud/MiniMax the prefix is intentionally preserved in the wire request.
• OrcaRouter only exposes chat completions; no embeddings/audio endpoints, so no other FunClip surface was touched.

Disclosure: I'm an engineer on the OrcaRouter team.