Core API routing and admin billing access.

Added Core API canary routing for selected app.molten.bot HTTP routes, with deploy-time VITE_CORE_API_URL wiring and tests for routing decisions.

Expanded Core API routing across auth login, registration, password reset, user profile, API key, LLM package, secrets, billing, Hub schedule, and communication route groups.

Let Cordia admins create projects and releases without billing authorization checks, with coverage confirming billing failures no longer block admin work.

Pointed Cordia QA and production MOLTEN_API_BASE settings at Molten Core API Gateway endpoints for direct Core-backed API traffic.