feat(Lightbox): touch zoom like the iOS Photos viewer

.changeset/lightbox-double-click-point.md

@@ -0,0 +1,7 @@
+---
+'@astryxdesign/core': patch
+---
+
+[fix] Lightbox: a double-click now zooms 2× about the clicked point instead of about the centre, and the next goes back; the keyboard keeps its 2× zoom about the centre.
+
+@vjeux

.changeset/lightbox-every-pointer.md

@@ -0,0 +1,7 @@
+---
+'@astryxdesign/core': patch
+---
+
+[feat] Lightbox: a ctrl-wheel or a trackpad pinch now zooms a photo, and a trackpad's scroll pans a zoomed photo.
+
+@vjeux

.changeset/lightbox-touch-zoom.md

@@ -0,0 +1,9 @@
+---
+'@astryxdesign/core': patch
+---
+
+[feat] Lightbox's zoom now works under a finger the way the iOS Photos viewer does, on a phone, a tablet or a touchscreen laptop. Pinch the photo to zoom around your fingers, and move them to pan while you zoom. Past the zoom limits the photo gives way, then springs back when you let go, at the speed your fingers had. Double-tap zooms until the photo fills the screen, at least 2×, and keeps the tapped point under your finger; double-tap again to go back. On a phone or a tablet, a zoomed photo pans with momentum, stretches past its edges and settles back. The keyboard keeps the zoom it had, 2× about the centre, and keyboard panning now stops at the photo's edges instead of carrying it out of view. Every zoom, a double tap's and a key's included, settles on the same spring.
+
+The photo's stage fills the viewer. A pinch on the photo no longer zooms the page, and a pinch on the controls or caption still does. With `hasZoom` on, a tap on the dark area beside the photo closes the viewer after the double-tap wait instead of at once; a click still closes it at once. The zoom animations run on the compositor, so they stay smooth while the page is busy. With `hasZoom` off, nothing changes. With `hasZoom`, Close, Previous, Next and the counter sit on a dark translucent backing, so they stay readable over a zoomed photo.
+
+@vjeux

.changeset/uikit-zoom-media.md

@@ -0,0 +1,7 @@
+---
+'@astryxdesign/core': patch
+---
+
+[chore] Internal: the UIKit constants table gains UIScrollView zooming for a photo viewer, measured on iOS 26.2. It holds the give past the zoom limits and Photos' aspect-fill double tap and maximum zoom. The zoom stage geometry that Lightbox's touch zoom is built on comes with it. Neither is exported from the package entry point, and Lightbox's touch zoom reads them.
+
+@vjeux

apps/storybook/stories/Lightbox.stories.tsx

@@ -104,6 +104,48 @@ export const WithZoom: Story = {
   },
 };
 
+/** Zoom on a photo with a caption, which sits under the fitted photo. */
+export const ZoomWithCaption: Story = {
+  render: () => {
+    const [isOpen, setIsOpen] = useState(false);
+    return (
+      <>
+        <button onClick={() => setIsOpen(true)}>Open zoom with caption</button>
+        <Lightbox
+          isOpen={isOpen}
+          onOpenChange={setIsOpen}
+          media={{
+            src: SAMPLE_IMAGE,
+            alt: 'Forest path',
+            caption: 'A winding path through the forest',
+          }}
+          hasZoom
+        />
+      </>
+    );
+  },
+};
+
+export const GalleryWithZoom: Story = {
+  render: () => {
+    const [isOpen, setIsOpen] = useState(false);
+    const [index, setIndex] = useState(0);
+    return (
+      <>
+        <button onClick={() => setIsOpen(true)}>Open gallery with zoom</button>
+        <Lightbox
+          isOpen={isOpen}
+          onOpenChange={setIsOpen}
+          media={GALLERY_MEDIA}
+          index={index}
+          onIndexChange={setIndex}
+          hasZoom
+        />
+      </>
+    );
+  },
+};
+
 export const WithCaption: Story = {
   render: () => {
     const [isOpen, setIsOpen] = useState(false);

packages/core/src/Lightbox/Lightbox.doc.mjs

@@ -98,7 +98,7 @@ export const docs = {
       name: 'hasZoom',
       type: 'boolean',
       description:
-        'Enable zoom on double-click, or Enter/Space/+/- via keyboard (images only). When zoomed, drag or use arrow keys to pan.',
+        'Enable zoom (images only): pinch (or ctrl-wheel), or double-tap or double-click to zoom in at that point and back; Enter/Space/+/- zoom 2× about the centre and back. When zoomed, drag or scroll a trackpad to pan, or use arrow keys; on a phone or a tablet, the pan has momentum.',
       default: 'false',
     },
     {
@@ -211,7 +211,8 @@ export const docsZh = {
     {
       name: 'hasZoom',
       type: 'boolean',
-      description: '启用双击缩放（仅图片）。缩放后可拖动平移。',
+      description:
+        '启用缩放（仅图片）：双指捏合（或按住 Ctrl 滚动滚轮），或双点按、双击在该处放大并还原；Enter/Space/+/- 键以中心放大 2 倍并还原。缩放后可拖动或在触控板上滚动平移，或用方向键平移；在手机或平板上，平移带惯性。',
       default: 'false',
     },
     {
@@ -296,7 +297,7 @@ export const docsDense = {
     index: 'Current index in gallery mode.',
     onIndexChange: 'Callback when gallery index changes.',
     hasZoom:
-      'Enable zoom (double-click, Enter/Space, or +/-) and pan (drag or arrow keys) for images.',
+      'Enable zoom (pinch or ctrl-wheel, double-tap or double-click, Enter/Space, or +/-) and pan (drag, trackpad scroll, or arrow keys) for images.',
     xstyle: 'StyleX styles for layout customization.',
   },
 };