feat: add OrcaRouter as a BYOK provider

[zhenjunchen-png]

Related Issue

Closes #1629

Description

Adds OrcaRouter (https://orcarouter.ai) as a dedicated BYOK provider card in Agents → Models. OrcaRouter is an OpenAI-compatible LLM gateway that routes each request to the cheapest or fastest provider across many upstream providers.

Follows the existing alias pattern used by ModelArk, grok, llama.cpp: provider id orcarouter is aliased to openai-compatible-model on the backend, so no ModelPlatformType / CAMEL changes are required.

Files

• backend/app/model/model_platform.py: PLATFORM_ALIAS_MAPPING entry ("orcarouter": "openai-compatible-model")
• src/lib/llm.ts: INIT_PROVODERS entry with default base URL https://api.orcarouter.ai/v1. Card is positioned at the end of the list to preserve the existing provider ordering for current users.
• src/assets/model/orcarouter.svg: official OrcaRouter brand logo
• src/pages/Agents/Models.tsx: import + register icon in getModelImage
• docs/core/models/byok.md: add row to Supported Providers table

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

Testing Evidence (REQUIRED)

End-to-end tested locally (dev: npm run dev):

1. Card appears at the end of the BYOK list under Custom Model with the OrcaRouter logo, name, and description.
2. API Host pre-fills to https://api.orcarouter.ai/v1.
3. Entered API key + a model_type, clicked Save → validation passed.
4. Set as default → header now shows "Custom Model / OrcaRouter ()".
5. Ran a project task → the request was served by OrcaRouter successfully.

npm run type-check and npx eslint both pass on the changed files; the existing npm run test results are unaffected (no test files touched).

Screenshot:

• I have included human-verified testing evidence in this PR.
• This PR includes frontend/UI changes, and I attached screenshot(s) or screen recording(s).
• No frontend/UI changes in this PR.

What is the purpose of this pull request?

• Bug fix
• New Feature
• Documentation update
• Other

Contribution Guidelines Acknowledgement

• I have read and agree to the Eigent Contribution Guideline

[zhenjunchen-png]

Closing for now — preparing additional changes to fold into the same integration. Will reopen with the updated scope. Thanks for your patience.