feat(media): introduce MediaRouter and stubs for image and speech generation

Refactor modal service and logging setup

feat: Implement well-known typed fields for verdicts in output models

fix(modal): shorten cascade slug to fit DNS limit; add endpoint health tooling

feat(logging): implement structured JSON logging for vLLM and enhance observability

feat: add Nemotron-Cascade-14B-Thinking model configuration to catalogue and README

feat: unify model catalogue and self-hosted routing

fix: update endpoint URLs to reflect new app naming conventions

feat: add OpenAPI docs and opt-in bearer auth via env-var secret

feat: add Modal model-serving layer, one app per provider