fix(capture): Zoom/Pan vs Rotate gesture modes; drop dead ↻ overlay

Pinch/drag were applying zoom and tilt together on Measure. Add an
explicit Zoom/Pan | Rotate segmented toggle (default Zoom/Pan). Stage
gestures are exclusive per mode; tilt/zoom sliders stay available.

Remove the bottom-center ↻ handle that sat on tick B (hitTick won, so
the icon looked live but only moved the tick).

frontend/src/capture/AxisPanel.svelte

@@ -76,7 +76,7 @@
         <button type="button" class="thumb" aria-label="Tilt right" on:click={() => nudgeTilt(1)}>+</button>
         <span class="val">{tiltShown}°</span>
       </div>
-      <p class="nudge">±90° · ← → tilt 1° · Shift+← → 0.1° · two-finger twist · or drag the ↻ handle</p>
+      <p class="nudge">±90° · ← → tilt 1° · Shift+← → 0.1° · two-finger twist (Rotate gesture mode)</p>
     </div>
 
     <div>