feat: auto-pan timeline to selected scan region when zoomed

When a scan result row is clicked, if the active region falls outside
the current zoomed view the view centers on the region (and widens if
the region is larger than the current span).

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

main.py

@@ -1776,8 +1776,26 @@ class TimelineWidget(QWidget):
 
     def set_active_scan_region(self, start: float, end: float) -> None:
         self._active_scan_region = (start, end)
+        self._ensure_range_visible(start, end)
         self.update()
 
+    def _ensure_range_visible(self, start: float, end: float) -> None:
+        """If a zoomed view is active and [start, end] is partially/fully outside
+        it, pan (and if needed widen) the view so the range is visible."""
+        if self._view_span <= 0 or self._duration <= 0:
+            return
+        span = self._view_span
+        # If the range is wider than the view, widen the view to fit it (+10% margin).
+        needed = (end - start) * 1.1
+        if needed > span:
+            span = min(self._duration, needed)
+            self._view_span = span
+        view_end = self._view_start + span
+        if start < self._view_start or end > view_end:
+            center = (start + end) / 2.0
+            self._view_start = center - span / 2.0
+            self._clamp_view()
+
     def clear_active_scan_region(self) -> None:
         if self._active_scan_region is not None:
             self._active_scan_region = None