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/test_editor_transform_skew_js.py

@@ -0,0 +1,44 @@
+from pathlib import Path
+
+ROOT = Path(__file__).resolve().parents[1]
+
+
+def read(rel):
+    return (ROOT / rel).read_text(encoding="utf-8")
+
+
+STATE = read("static/js/editor/state.js")
+POPUP = read("static/js/editor/build/transform-popup.js")
+SESSION = read("static/js/editor/tools/transform-session.js")
+MULTI = read("static/js/editor/multi-transform.js")
+
+
+def test_state_has_skew_fields():
+    assert "transformPendingSkewX: 0" in STATE
+    assert "transformPendingSkewY: 0" in STATE
+
+
+def test_popup_exposes_skew_fields():
+    assert 'id="ge-transform-skew-x"' in POPUP
+    assert 'id="ge-transform-skew-y"' in POPUP
+    assert 'data-spin-for="ge-transform-skew-x"' in POPUP
+    assert 'data-spin-for="ge-transform-skew-y"' in POPUP
+
+
+def test_session_threads_skew_through_transform():
+    assert "state.transformPendingSkewX" in SESSION
+    assert "state.transformPendingSkewY" in SESSION
+    assert "'#ge-transform-skew-x': state.transformPendingSkewX" in SESSION
+    assert "skewX: state.transformPendingSkewX" in SESSION
+    assert "state.transformPendingSkewX = target.skewX" in SESSION
+    assert "Math.tan((geometry.skewX" in SESSION
+    assert "Math.tan((geometry.skewY" in SESSION
+
+
+def test_multitransform_geometry_carries_skew():
+    assert "target.skewX || 0" in MULTI
+    assert "target.skewY || 0" in MULTI
+    assert "skewPadX" in MULTI
+    assert "skewPadY" in MULTI
+    assert "skewX," in MULTI
+    assert "skewY," in MULTI