[verified] fix: make swarm router dispatch nonblocking

[im-khang]

Summary

• make Router Chat dispatch non-blocking by sending waitForCheckpoint: false
• add bounded browser-side timeouts for decompose and dispatch requests
• fix /api/swarm-decompose gateway auth to use the runtime bearer token helper
• add regression tests for Router Chat dispatch behavior and swarm-decompose auth wiring

Test Plan

• npm -s test -- src/components/swarm/router-chat.test.ts src/routes/api/-swarm-decompose.test.ts src/routes/api/-swarm-dispatch.test.ts
• Runtime local verification: POST /api/swarm-decompose returned ok: true, fallback: false, and model-generated assignments
• Browser smoke: /swarm loaded, Router Chat accepted prompt, Route mission button enabled

Notes

• npm run check is currently blocked by an unrelated baseline syntax error in src/screens/playground/components/playground-hud.tsx.