feat: add OrcaRouter as a BYOK provider with a searchable model picker

[zhenjunchen-png]

Related Issue

Closes #1631

Description

Adds OrcaRouter (https://www.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.

This PR additionally introduces two generic primitives on the Provider type:

• modelsEndpoint — when set, the card renders a searchable model dropdown instead of a free-form text input.
• websiteUrl — when set, the card renders a small "Visit " link inline after the description.

Only OrcaRouter opts in to both in this PR; all other existing providers (OpenAI, Anthropic, OpenRouter, …) are unchanged.

Files

• backend/app/model/model_platform.py: PLATFORM_ALIAS_MAPPING entry ("orcarouter": "openai-compatible-model").
• src/types/index.ts: add optional modelsEndpoint?: string and websiteUrl?: string to the Provider type. Generic fields; no behavior change for existing providers.
• src/lib/llm.ts: INIT_PROVODERS entry with default base URL https://api.orcarouter.ai/v1, modelsEndpoint: '/models', and websiteUrl: 'https://www.orcarouter.ai'. Card is positioned immediately after Anthropic (above OpenRouter) so the two gateway-style providers sit together.
• src/assets/model/orcarouter.svg: official OrcaRouter brand logo.
• src/pages/Agents/Models.tsx: cloud-provider model fetch state, conditional render (Combobox when modelsEndpoint is set, original Input otherwise), inline "Visit " link rendering, plus icon import / register in getModelImage.
• src/lib/providerModels.ts (new): fetchProviderModels (Bearer-auth GET + filter chat-capable + group by id prefix) and localStorage cache helpers.
• src/pages/Agents/components/ProviderModelCombobox.tsx (new): Popover + Command-based combobox; left column lists upstream providers (<prefix> of <prefix>/<model>), right column shows that provider's models with search filter; refresh button next to the trigger.
• 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 (node node_modules/vite/bin/vite.js):

1. Card placement: OrcaRouter appears immediately after Anthropic, above OpenRouter, with the OrcaRouter logo and pre-filled https://api.orcarouter.ai/v1 API host.
2. Empty API key state: Model Type combobox trigger and refresh button are disabled with a clear "Enter API Key first." helper inside the popover.
3. Refresh: with a valid API key entered, the refresh icon shows a spinner; on success, the left column populates with upstream provider tabs (anthropic / deepseek / google / grok / kimi / minimax / openai / qwen, each with a model count) and the right column populates with the active provider's models.
4. Search: typing in the search box narrows the active provider's right-column list.
5. Selection: choosing a model closes the popover and the trigger shows the full <provider>/<model> id.
6. Save + set as default: header shows "Custom Model / OrcaRouter ()".
7. Project task run: agent request was served by OrcaRouter successfully.
8. Cache: closing and re-opening the app restores the model list from localStorage (keyed per provider id) without re-fetching; explicit refresh re-syncs.

npm run type-check and npx eslint both pass on the changed files; existing test files were not touched.

Screenshot: drag the local Models-page screenshot into this section after opening the PR — GitHub will upload it to user-attachments automatically.

• 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