[codex] add concierge routing v1

[furukama]

Summary

• add Concierge Routing V1 for ambiguous long-running interactive requests
• add routing.concierge runtime config for the concierge model and the three execution-profile model mappings
• integrate gateway-side pending concierge state so a 1/2/3 follow-up resumes the original request with the selected profile model

What Changed

• added a new concierge routing helper module for trigger detection, urgency inference, small-model decision parsing, and profile-to-model resolution
• wired the gateway request flow to ask the fixed urgency question only when needed, bypass concierge routing for explicit model pins, and resume the original request after the user's choice
• added targeted tests for the router helpers and the end-to-end gateway follow-up flow

Validation

• ./node_modules/.bin/vitest tests/gateway-concierge-routing.test.ts tests/gateway-service.concierge.test.ts
• npm run typecheck

Scope Boundaries

• interactive-only v1
• no scheduler or background execution changes
• no /routing model ... command surface in this step