feat: rampart-tui — live metrics terminal dashboard

- ratatui + crossterm; separate bin reading Prometheus exposition format
- counter table (xdp stats, auto-bans, intel), pps/drops history chart,
  status panel with error banner, q/quit r/refresh
- prometheus text parser (labels, escapes, NaN/Inf), Fetcher trait for tests
- 152 tests green

src/lib.rs

@@ -8,4 +8,5 @@ pub mod metrics;
 pub mod protocol;
 pub mod store;
 pub mod traffic;
+pub mod tui;
 pub mod xdp;