Gate pinch zoom behind an existing zoom

A two-finger pinch only changes scale once the photo is already zoomed
in; at 100% the gesture is inert, so the paging strip keeps behaving
like a plain gallery. The responder is now held for the whole pinch so
the paging ScrollView cannot steal it mid-gesture.

src/components/ZoomableImage.tsx

@@ -6,6 +6,8 @@ import { Animated, PanResponder } from 'react-native';
 // While zoomed in, responder termination is refused so the parent ScrollView
 // cannot steal the gesture — the photo pans instead of paging; swiping to the
 // next photo resumes after zooming back out (double tap or pinch below 1.15).
+// Two-finger pinch only zooms once the photo is already zoomed in: at 100% the
+// pinch stays inert, so the paging strip still behaves like a plain gallery.
 //
 // ponytail: pinch zooms around the image center, not the finger midpoint;
 // focal zoom needs per-touch location math against the image's screen rect.
@@ -99,7 +101,8 @@ export default function ZoomableImage({ uri, width }: ZoomableImageProps) {
       onMoveShouldSetPanResponder: () => true,
       // Page the strip while zoom is off; once zoomed (or mid-pinch) the
       // image keeps the gesture for panning/zooming itself.
-      onPanResponderTerminationRequest: () => st.scale <= 1.001,
+      onPanResponderTerminationRequest: () =>
+        st.scale <= 1.001 && st.pinchStart === null,
       onPanResponderGrant: () => {
         st.grantAt = Date.now();
         st.moved = false;
@@ -113,10 +116,13 @@ export default function ZoomableImage({ uri, width }: ZoomableImageProps) {
           const b = touches[1];
           const dist = Math.hypot(a.pageX - b.pageX, a.pageY - b.pageY);
           if (!st.pinchStart) st.pinchStart = { scale: st.scale, dist: dist || 1 };
-          const next = Math.max(
-            1,
-            Math.min(MAX_SCALE, st.pinchStart.scale * (dist / st.pinchStart.dist))
-          );
+          const next =
+            st.pinchStart.scale > 1.001
+              ? Math.max(
+                  1,
+                  Math.min(MAX_SCALE, st.pinchStart.scale * (dist / st.pinchStart.dist))
+                )
+              : 1;
           st.scale = next;
           if (next <= 1.001) {
             st.tx = 0;