feat(tui): add time-based graph navigation and zooming

Implement a scrollable and zoomable viewport for the TUI graphs, allowing users to pan through historical data using arrow keys and adjust the time window with zoom controls. This transitions graph rendering from sample-count based to timestamp-based for more accurate temporal visualization.

crates/irtt-cli/src/cmd/tui/run.rs

@@ -318,7 +318,7 @@ fn handle_input(state: &mut TuiState, shutdown_requested: &AtomicBool) -> io::Re
                 state.toggle_pause();
                 force_render = true;
             }
-            KeyCode::Char('g') => {
+            KeyCode::Char('g') | KeyCode::Char('m') => {
                 state.cycle_graph_mode();
                 force_render = true;
             }
@@ -330,6 +330,42 @@ fn handle_input(state: &mut TuiState, shutdown_requested: &AtomicBool) -> io::Re
                 state.toggle_full_graph();
                 force_render = true;
             }
+            KeyCode::Left => {
+                state.pan_graph_left();
+                force_render = true;
+            }
+            KeyCode::Right => {
+                state.pan_graph_right();
+                force_render = true;
+            }
+            KeyCode::PageUp => {
+                state.pan_graph_page_left();
+                force_render = true;
+            }
+            KeyCode::PageDown => {
+                state.pan_graph_page_right();
+                force_render = true;
+            }
+            KeyCode::Home => {
+                state.jump_graph_oldest();
+                force_render = true;
+            }
+            KeyCode::End => {
+                state.jump_graph_live();
+                force_render = true;
+            }
+            KeyCode::Char('+') | KeyCode::Char('=') => {
+                state.zoom_graph_in();
+                force_render = true;
+            }
+            KeyCode::Char('-') => {
+                state.zoom_graph_out();
+                force_render = true;
+            }
+            KeyCode::Char('0') => {
+                state.reset_graph_window();
+                force_render = true;
+            }
             _ => {}
         }
     }