perf: batch TUI refreshes and render only visible cards

[swananan]

Every incoming trace or runtime status previously triggered a redraw, and each redraw formatted the entire retained history, including when a single card was expanded. Batch incoming messages and cap redraws at 60 FPS, while flushing the final pending frame after a burst and avoiding redraws while idle.

Build cards around the visible viewport, with bounded lookahead for variable heights, and format only the selected card in expanded view. Preserve scrolling and truncation, and keep the latest or selected card visible when the panel is shorter than a full card. Add seven renderer regression tests covering bounded formatting work, resizing, scrolling, expanded views, truncation, and minimal viewports.

Local renderer benchmark: debug build, 100×40 Ratatui TestBackend, 2,000 synthetic trace events, 50 warmup draws and 500 measured draws. Median redraw times:

View	Before	After
Auto-refresh list	15.373 ms	1.889 ms
Manual-scroll list	15.462 ms	2.020 ms
Expanded card	12.680 ms	1.189 ms

The updated auto-refresh list takes about 1.89 ms with either 20 or 2,000 retained events.

Validation completed on the same source tree as this PR:

• cargo fmt --all
• cargo clippy --all-targets --all-features -- -D warnings
• cargo test -p ghostscope-ui --all-features: 157 passed
• Standard host-to-host e2e: 373 passed, 0 failed, 0 ignored
• PTY checks of the real TUI: final-frame flush after a burst, no idle redraws, bounded redraw frequency, and responsive shutdown during an event stream

Container-topology e2e was intentionally skipped because this change does not affect container behavior.