Add ZooPost dry-run dashboard and agent bridge

[hthmkt12]

Summary

• Add ZooPost dashboard shell and dry-run Auto Post Fanpage UI.
• Route ZooPost Cloud dev API prefixes separately from local FBKit routes, with server-side-only dev bearer support.
• Add local ZooPost gateway dry-run dispatch adapter with idempotent task creation and safe payload filtering.
• Add live account lease heartbeat refresh docs/tests and dashboard WebSocket reconnect regression coverage.

Safety

• Keeps FBKit live/social mutation disabled by default.
• ZooPost dispatch adapter forces local tasks to dry-run and strips server-owned/live markers.
• Cloud media inputs reject filesystem paths and keep opaque refs only.

Validation

• Dashboard build, lint, and Vitest passed.
• Backend focused pytest suite passed: account queue/quota, ZooPost adapter, rollout gate docs.
• Agent Python compileall passed.
• Safe local smoke passed: dashboard proxy routed FBKit status locally, cloud prefixes to ZooPost Cloud, and publish job creation stayed dry-run only.