Annotator (#1861)

<!-- This is an auto-generated description by cubic. -->
## Summary by cubic
Adds an in-app screenshot annotator to the Preview panel for Pro users
so you can capture the current app view, draw or add text, and submit an
annotated image to chat.

- **New Features**
- Pen button in PreviewIframe to toggle annotator; captures a screenshot
via worker messaging and displays it in a Konva canvas.
- Tools: select, freehand draw, and draggable text; supports undo/redo,
delete, and resizing with Transformer. Canvas scales to the container.
Includes a color picker.
- Submit exports a PNG and attaches it to the chat via useAttachments;
prefills the chat input; annotator auto-closes after submit.
  - Pro-only: non-Pro users see an upsell screen.
- State atoms added: annotatorModeAtom, screenshotDataUrlAtom,
attachmentsAtom; PreviewIframe now handles dyad-screenshot-response
messages.

- **Dependencies**
  - Added konva, react-konva, perfect-freehand, and html-to-image.
- Proxy now injects html-to-image and the new dyad-screenshot-client.js
for screenshot capture.

<sup>Written for commit 580aca271c5993a0dc7426e36e34393e073bd67b.
Summary will update automatically on new commits.</sup>

<!-- End of auto-generated description by cubic. -->

package.json

@@ -145,17 +145,21 @@
     "framer-motion": "^12.6.3",
     "geist": "^1.3.1",
     "glob": "^11.0.2",
+    "html-to-image": "^1.11.13",
     "isomorphic-git": "^1.30.1",
     "jotai": "^2.12.2",
     "kill-port": "^2.0.1",
+    "konva": "^10.0.12",
     "lexical": "^0.33.1",
     "lexical-beautiful-mentions": "^0.1.47",
     "lucide-react": "^0.487.0",
     "monaco-editor": "^0.52.2",
     "openai": "^4.91.1",
+    "perfect-freehand": "^1.2.2",
     "posthog-js": "^1.236.3",
-    "react": "^19.2.1",
-    "react-dom": "^19.2.1",
+    "react": "^19.0.0",
+    "react-dom": "^19.0.0",
+    "react-konva": "^19.2.1",
     "react-markdown": "^10.1.0",
     "react-resizable-panels": "^2.1.7",
     "react-shiki": "^0.9.0",