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/quick-select.js

@@ -0,0 +1,63 @@
+// Quick Selection brush — drag to grow a wand-style selection.
+// Reuses the existing magic-wand flood fill by re-sampling along the
+// stroke; intermediate samples skip the undo snapshot (retune mode) so a
+// whole drag collapses to one history entry (taken on begin).
+
+import { selectionModeForEvent } from '../selection-modifiers.js';
+
+export function createQuickSelectTool({
+  activeLayer,
+  saveState,
+  composite,
+  runMagicWand,
+  canvasCoords,
+  brushSize,
+  syncToolClearIndicators,
+}) {
+  let painting = false;
+  let last = null;
+
+  const modeFor = (event) => selectionModeForEvent(event, 'add');
+
+  const sample = (event) => {
+    const coords = canvasCoords(event);
+    if (!coords) return;
+    runMagicWand(coords.x, coords.y, modeFor(event), { retune: true });
+  };
+
+  const begin = (event) => {
+    const layer = activeLayer();
+    if (!layer) return;
+    saveState();
+    painting = true;
+    last = null;
+    sample(event);
+    const coords = canvasCoords(event);
+    if (coords) last = coords;
+  };
+
+  const drag = (event) => {
+    if (!painting) return;
+    const coords = canvasCoords(event);
+    if (!coords) return;
+    const gap = Math.max(3, (brushSize?.() || 24) / 4);
+    if (last && Math.hypot(coords.x - last.x, coords.y - last.y) < gap) return;
+    sample(event);
+    last = coords;
+  };
+
+  const end = () => {
+    if (!painting) return;
+    painting = false;
+    last = null;
+    composite();
+    syncToolClearIndicators?.();
+  };
+
+  const cancel = () => {
+    painting = false;
+    last = null;
+  };
+
+  return { begin, drag, end, cancel };
+}