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>

tests/e2e/photo-editor/phone-footer-gaps.spec.js

@@ -0,0 +1,40 @@
+const { test, expect } = require('@playwright/test');
+const { openBlankEditor } = require('./helpers');
+
+test.use({ viewport: { width: 390, height: 844 }, hasTouch: true });
+
+async function gaps(page) {
+  return page.evaluate(() => {
+    const rect = selector => document.querySelector(selector).getBoundingClientRect();
+    const canvas = rect('.ge-main-canvas');
+    const footer = rect('.ge-editor-footer');
+    const sheet = rect('.ge-right-panel');
+    return {
+      canvasToFooter: Math.abs(canvas.bottom - footer.top),
+      footerToSheet: Math.abs(footer.bottom - sheet.top),
+      footerLeft: footer.left,
+      footerRight: footer.right,
+      sheetTop: sheet.top,
+    };
+  });
+}
+
+test('mobile footer docks flush between the canvas and the layers sheet', async ({ page }) => {
+  await openBlankEditor(page, { width: 640, height: 480 }, 'Mobile footer dock');
+  await page.locator('.ge-tour-close').click({ timeout: 500 }).catch(() => {});
+
+  await expect(page.locator('.ge-editor-footer')).toHaveClass(/ge-footer-floating/);
+  await expect(page.locator('.ge-layers-grab')).toBeHidden();
+
+  // Wait until the dock has settled: canvas bottom == footer top == sheet top.
+  await expect.poll(async () => {
+    const g = await gaps(page);
+    return g.canvasToFooter <= 2 && g.footerToSheet <= 2;
+  }, { timeout: 10_000 }).toBe(true);
+
+  const g = await gaps(page);
+  expect(g.canvasToFooter).toBeLessThanOrEqual(2);
+  expect(g.footerToSheet).toBeLessThanOrEqual(2);
+  expect(g.footerLeft).toBeLessThanOrEqual(1);
+  expect(Math.abs(g.footerRight - 390)).toBeLessThanOrEqual(1);
+});