feat(app): add version number in footer, add app header bar

[andrewmelchor]

Summary

Add app version in footer

[greptile-apps]

Greptile Summary

This PR restructures the TUI layout by introducing a new HeaderBar component at the top of the screen (displaying the app name and connection status) and moving the version number (v{Installation.VERSION}) into the StatusBar footer. The StatusBar is simplified by removing duplicate "t-req" branding and connection status indicators, which are now owned by HeaderBar.

Key changes:

• New HeaderBar component — renders the app title on the left and connection status (icon + text) on the right, placed above the main SplitPanel in app.tsx.
• StatusBar refactor — removes "t-req" label and connection status; consolidates all keybind hints into the left flex group; adds v{Installation.VERSION} on the right.
• app.tsx — adds import and rendering of HeaderBar at the top of FullScreenLayout.

Issue found: The outer <box> in HeaderBar declares height={2} while containing only a single <box height={1}> child, wasting one terminal row with empty background color.

Confidence Score: 3/5

• Safe to merge after fixing the HeaderBar outer box height, which currently wastes one terminal row.
• The changes are straightforward UI restructuring with no data-flow or state-management risk. The layout integration is correct and the version number placement is clean. The only concrete issue is the mismatched height on the HeaderBar outer box (height=2 containing a single height=1 child), which silently wastes one visible terminal row. This is a real visual bug but does not cause crashes or data loss.
• packages/app/src/tui/components/header-bar.tsx — fix the outer box height declaration to match its single child or add padding content.

_{Last reviewed commit: 1f54c54}