feat: add OrcaRouter as an LLM provider

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Description

This PR adds OrcaRouter as a new OpenAI-compatible
provider — one sk-orca- key gets you GPT-5, Claude Opus 4.7, Gemini 3, DeepSeek
V4, Grok, Qwen, MiniMax and ~120 other chat models across 9 vendors. There's also
an orcarouter/auto virtual model that adaptively routes each request based on
a configurable cheapest / balanced / quality / contextual-bandit / difficulty-gated
strategy.

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

Followed the same patterns as CometAPI (#7809), ClawRouter (#11751), and
Tensorix (#11184), including the User-Agent: Continue/IDE and
X-Continue-Provider: orcarouter attribution headers introduced by ClawRouter.

What's in the PR

Core (core/)

• core/llm/llms/OrcaRouter.ts — provider class extending OpenAI; injects
  attribution headers and reuses the existing Anthropic cache_control
  pass-through for Claude models
• core/llm/llms/index.ts — register in LLMClasses
• core/llm/autodetect.ts — added to PROVIDER_HANDLES_TEMPLATING and
  PROVIDER_SUPPORTS_IMAGES
• core/llm/toolSupport.ts — per-model tool-calling whitelist; skips image-only
  models that occasionally appear in orcarouter/auto's default routing pool
• core/control-plane/schema.ts — schema validation for Continue Hub

Adapter package (packages/openai-adapters/)

• packages/openai-adapters/src/apis/OrcaRouter.ts — adapter class exporting
  ORCAROUTER_HEADERS
• packages/openai-adapters/src/apis/AiSdk.ts — register in PROVIDER_MAP
• packages/openai-adapters/src/index.ts / src/types.ts — factory wiring and
  zod literal

UI (extensions/vscode/, gui/)

• extensions/vscode/config_schema.json — provider enum + description
• gui/src/pages/AddNewModel/configs/{providers,models}.ts — provider card
  with 8 vendor-prefixed presets (OrcaRouter Auto, OpenAI: GPT-5.5,
  Anthropic: Claude Opus 4.7, Google: Gemini 3 Flash Preview,
  DeepSeek: DeepSeek V4 Pro, xAI: Grok 4.3, Alibaba: Qwen 3.6 Flash,
  MiniMax: MiniMax M2.7) plus an AUTODETECT fallback that calls
  GET /v1/models against the user's apiBase
• gui/public/logos/orcarouter.png — logo (1024×1024)

Docs (docs/)

• docs/customize/model-providers/more/orcarouter.mdx — usage docs with
  reasoning_effort / Anthropic thinking block / extra_body fallback chain
  examples plus the AUTO router tool-calling caveat
• docs/customize/model-providers/overview.mdx — Hosted Services table row
• docs/docs.json — sidebar entry under "More Providers"

AI Code Review

• Team members only: AI review runs automatically when PR is opened or marked ready for review
• Team members can also trigger a review by commenting @continue-review

Checklist

• I've read the contributing guide
• The relevant docs, if any, have been updated or created
• The relevant tests, if any, have been updated or created

Screen recording or screenshot

continue-v2-compressed.mp4

Tests

• core/llm/llms/OrcaRouter.vitest.ts — 7 cases covering provider name,
  default options, attribution header injection, user header override, and
  Anthropic prompt-caching pass-through (patterned on OpenRouter.vitest.ts).
• packages/openai-adapters/src/apis/OrcaRouter.test.ts — 4 cases covering
  default apiBase, custom apiBase override, attribution headers, and standard
  OpenAI headers (patterned on ClawRouter.test.ts).
• Manually smoke tested inside the VS Code dev host with a real sk-orca- key
  across chat / agent / edit flows; screencast attached above.

[github-actions]

All contributors have signed the CLA ✍️ ✅
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I have read the CLA Document and I hereby sign the CLA

[cubic-dev-ai]

No issues found across 18 files

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