feat: OpenRouter provider routing and reasoning control

[chiefmojo]

Problem

When using OpenRouter as the LLM provider, operators have no way to:

1. Exclude specific upstream providers from serving requests (provider.ignore)
2. Set a preferred provider order (provider.order)
3. Control reasoning effort per model slot (reasoning)

All three are standard OpenRouter-specific request fields that MemOS currently passes through to the HTTP body without any config surface.

Changes

Config schema — adds providerIgnore, providerOrder, and reasoning to LlmSchema and SkillEvolverSchema:

llm:
  provider: openai_compatible
  endpoint: https://openrouter.ai/api/v1
  apiKey: sk-...
  providerIgnore:
    - together
    - deepinfra
  providerOrder:
    - anthropic
    - google
  reasoning:
    enabled: true
    max_tokens: 8000

SkillEvolverSchema:
  provider: openai_compatible
  endpoint: https://openrouter.ai/api/v1
  providerIgnore:
    - novita

Provider layer — openai.ts detects OpenRouter endpoints and injects the provider routing object; reasoning is forwarded unconditionally when set. Non-OpenRouter endpoints are unaffected.

Embedding — providerIgnore/providerOrder added to the embedding config schema; openai.ts embedding provider applies the same routing logic.

Pipeline — bootstrapMemoryCore forwards the new fields to createLlmClient for the skillEvolver slot.

Tests

• providers.test.ts — reasoning forwarding, routing injection for non/streaming calls, non-OpenRouter passthrough
• bootstrap-llm-config.test.ts — verifies routing fields propagate to dedicated LLM clients
• load.test.ts — defaults to empty arrays, accepts explicit values