feat(editor): add image insertion with OCR support and size limit handling

Add image button with dropdown menu for uploading local images or inserting from URL.
Integrate VLM-based OCR to extract text context from images and include in AI suggestions.
Implement document size limits to disable AI when exceeding threshold.
Refactor copilot plugin with per-view runtime state and OCR context injection.
Add OCR cache utility for managing image metadata.
Add code splitting configuration for optimized bundle size.

src/style.css

@@ -72,5 +72,6 @@ body {
   padding: 0;
   width: 100%;
   height: 100%;
-  overflow: hidden;
+  overflow-x: hidden;
+  overflow-y: auto;
 }