fix(tui): make PS panel detail updates non-blocking for responsive UI

[proboscis]

Summary

• Fix PS panel responsiveness by making detail panel updates non-blocking
• Add loading indicators to Stats/Issue/Changes tabs while data is being fetched
• Apply same async pattern to OrchMonitorApp for consistency

Problem

The PS panel had severe responsiveness issues:

• Slow table loading
• UI freezes during data fetch
• Tabs remained empty while data was loading

Root Cause: _update_run_detail_panel made blocking calls (HTTP requests, subprocess calls, daemon API) on the main UI thread.

Solution

Split detail panel updates into two phases:

1. Immediate update (non-blocking):

   • Show run metadata from Run object (Status, Elapsed, Agent, Model, Branch, PR URL)
   • Display loading indicators for async content
   • Show Changes tab data immediately (already in Run object)

2. Async fetch (background worker):

   • Fetch chat messages for opencode runs (HTTP request)
   • Capture session output for tmux sessions (subprocess)
   • Fetch issue details from daemon API
   • Update UI via call_from_thread when data arrives

Changes

runs_dashboard.hy

• New _update_run_detail_panel_immediate: Shows data without blocking calls
• New _fetch_additional_detail_data: Worker to fetch chat/session/issue data async
• New _apply_additional_detail_data: Updates tabs with fetched data
• Modified _set_selected_run: Calls immediate update then triggers async fetch

orch_monitor_app.hy

• New _show_run_detail_immediate: Shows immediate data with loading indicator
• New _fetch_run_session_output: Worker to fetch session output async
• New _apply_run_session_output: Updates detail panel with fetched data
• Modified _show_run_detail_callback: Uses new async pattern

Acceptance Criteria

• PS panel table loads within 1 second - table now loads immediately
• UI remains responsive during data fetch - async workers handle blocking calls
• Stats tab shows run metadata when run is selected - immediate display
• Issue tab shows issue details when run is selected - loading indicator then async update
• Changes tab shows diff stats when run is selected - immediate from Run object

Testing

• Hy files compile successfully
• Existing tests pass (17 failures are pre-existing, unrelated to this change)
• Code follows existing patterns using Textual's @work decorator

Fixes orch-379