feat: add OrcaRouter as a named embedding provider

[JinhaoSong322]

📋 Description

Add OrcaRouter as a first-class, named embedding provider, mirroring the existing siray/minimax OpenAI-compatible adapter pattern.

OrcaRouter is an OpenAI-compatible AI gateway at https://api.orcarouter.ai/v1 (API keys start with sk-orca-). 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.

Python SDK (openmemory-py)

• New OrcaRouterAdapter (chat + single/batch embeddings via the OpenAI-compatible API)
• Env config: ORCAROUTER_API_KEY, OM_ORCAROUTER_BASE_URL (default https://api.orcarouter.ai/v1), OM_ORCAROUTER_MODEL, OM_ORCAROUTER_EMBEDDING_MODEL
• emb_dispatch() routes the orcarouter provider

JS SDK / server (openmemory-js)

• env exposes orcarouter settings (base URL defaults to https://api.orcarouter.ai/v1)
• emb_orcarouter() / emb_batch_orcarouter() for single and batch embeddings
• get_model() resolves per-sector defaults from models.yml
• getEmbeddingInfo() reports orcarouter config; simple-mode batch path enabled

Dashboard

• Settings page lists orcarouter in the embedding provider select and adds OrcaRouter base URL / model override / API key fields
• Settings API masks ORCAROUTER_API_KEY

Config / docs

• models.yml per-sector orcarouter defaults
• .env.example, docs/mcp.md, README.md updated

🔄 Type of Change

• ✨ New feature (non-breaking change which adds functionality)
• 📚 Documentation update
• 🧪 Test updates

🧪 Testing

• I have tested this change locally
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

Python: tests/test_orcarouter.py (18 unit tests) + existing test_minimax.py / test_omnibus.py all pass (27 passed, 3 skipped — identical to a clean upstream checkout). JS: full vitest suite passes (9 files / 47 tests). Live test against the OrcaRouter API (/v1/chat/completions + /v1/embeddings) returns HTTP 200 with the real key.

🔍 Code Review Checklist

• Code follows the project's coding standards
• Self-review of the code has been performed
• Code is properly commented, particularly in hard-to-understand areas
• Changes generate no new warnings
• Any dependent changes have been merged and published

📚 Related Issues

N/A

🚀 Deployment Notes

No deployment changes required. Users opt in by setting OM_EMBEDDINGS=orcarouter and ORCAROUTER_API_KEY.

📋 Additional Context

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

[nullure]

LGTM