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_document_codec_js.py

@@ -58,6 +58,8 @@ def test_document_codec_preserves_advanced_layer_state():
         "gridSize": 24,
         "snapEnabled": True,
         "snapToGrid": True,
+        "autoSelectLayer": False,
+        "autoSelectTarget": "layer",
         "guides": {"vertical": [12, 70], "horizontal": [9]},
     }
     assert layer["blendMode"] == "multiply"
@@ -134,6 +136,8 @@ def test_document_codec_sanitizes_precision_view_state():
         "gridSize": 1000,
         "snapEnabled": True,
         "snapToGrid": False,
+        "autoSelectLayer": False,
+        "autoSelectTarget": "layer",
         "guides": {"vertical": [10, 20], "horizontal": [7]},
     }