Update app docs and status filters

[Curtis Summers (csummers)]

Summary

• Refresh Hot App and agent documentation to match the current navigation, dashboard, Workflows & Agents, Stores, schedules, MCP services, and project views
• Update the README’s description of Hot and clarify the public repo/cloud boundary
• Enable filtering runs by pending_retry
• Add cancelled to task status filters and correct the “All Statuses” behavior
• Remove 14 outdated Hot App screenshots