Editor: font-size presets + image insert/export support

Two editor features that were in flight alongside the sound work:
- FontSize TipTap extension (rides on textStyle) with Small/Normal/Large/
  Title presets in the toolbar; StatusBar + CSS support
- Image handling: internal/images handler, upload route + config, client
  API, EditorCore wiring, and md/html/docx export support for images

Claude-Session: https://claude.ai/code/session_016Yr6jELuRc7hyzYLccQKZd

web/package.json

@@ -12,7 +12,15 @@
   },
   "dependencies": {
     "@tiptap/extension-character-count": "^2.11.5",
+    "@tiptap/extension-color": "^2.27.2",
+    "@tiptap/extension-highlight": "^2.27.2",
+    "@tiptap/extension-image": "^2.27.2",
+    "@tiptap/extension-link": "^2.27.2",
     "@tiptap/extension-placeholder": "^2.11.5",
+    "@tiptap/extension-table": "^2.27.2",
+    "@tiptap/extension-table-cell": "^2.27.2",
+    "@tiptap/extension-table-header": "^2.27.2",
+    "@tiptap/extension-table-row": "^2.27.2",
     "@tiptap/extension-text-align": "^2.11.5",
     "@tiptap/extension-underline": "^2.11.5",
     "@tiptap/pm": "^2.11.5",