feat(photo-editor): Ajax Image Editor client (Photoshop-parity tools)

Photoshop-parity editor client: layers, selection/masking, brushes,
smart filters, LUT import, Quick Edit, mobile gestures, workspaces,
batch operations, and the service-worker versioning (v978->v1006).

Source: vendor/photocraft (ad1cff44) photo-editor client files, merged
onto upstream/dev (a8c147b2). Conflict resolution documented in
pr_work/A_conflicts.md; editor files taken from vendor/photocraft
(upstream's editor is an earlier snapshot of the same feature).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

static/js/editor/tools/patch.js

@@ -0,0 +1,69 @@
+// Patch tool — with a selection active, drag from inside it to a clean
+// source region; on release the selected content is replaced by that
+// source region (feathered at the seam). The pixel work lives in
+// ../patch-ops.js; this module only tracks the drag offset.
+//
+// begin()/drag()/end() are dispatched from the canvas event handler the
+// same way as the object-selection brush.
+
+import { state } from '../state.js';
+
+export function createPatchTool({
+  activeLayer,
+  canvasCoords,
+  saveState,
+  showToast,
+  onApply,
+}) {
+  let active = false;
+  let start = null;
+
+  const begin = (event) => {
+    const layer = activeLayer();
+    if (!layer) {
+      showToast?.('Select a layer to patch');
+      return;
+    }
+    if (!state.wandMask) {
+      showToast?.('Make a selection, then drag the Patch tool to a source area');
+      return;
+    }
+    const coords = canvasCoords(event);
+    if (!coords) return;
+    start = coords;
+    state.patchDx = 0;
+    state.patchDy = 0;
+    active = true;
+    if (state.mainCanvas) state.mainCanvas.style.cursor = 'copy';
+  };
+
+  const drag = (event) => {
+    if (!active || !start) return;
+    const coords = canvasCoords(event);
+    if (!coords) return;
+    state.patchDx = Math.round(coords.x - start.x);
+    state.patchDy = Math.round(coords.y - start.y);
+  };
+
+  const end = () => {
+    if (!active) return;
+    active = false;
+    start = null;
+    if (state.mainCanvas) state.mainCanvas.style.cursor = '';
+    const dx = Number(state.patchDx) || 0;
+    const dy = Number(state.patchDy) || 0;
+    state.patchDx = 0;
+    state.patchDy = 0;
+    if (dx === 0 && dy === 0) return;
+    saveState?.('Patch');
+    onApply?.(dx, dy);
+  };
+
+  const cancel = () => {
+    active = false;
+    start = null;
+    if (state.mainCanvas) state.mainCanvas.style.cursor = '';
+  };
+
+  return { begin, drag, end, cancel };
+}