Replace the composer textarea with a Tiptap markdown editor

The composer now writes markdown with bold, italic, strike, code,
links, quotes and lists, from shortcuts, markdown typing or a bubble
over the selection. @ mentions a bot and # a workspace, shown as chips
and saved as [bot:ID] / [workspace:ID]. Text selected in a message can
be quoted into the composer. User messages render as markdown, and
replies tell the bot who and what the user mentioned.

Adds an ESM stand-in for use-sync-external-store, since bunext keeps
React external in page bundles and the CommonJS original requires it.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

package.json

@@ -36,10 +36,18 @@
         "typescript": "^7.0.2"
     },
     "dependencies": {
+        "@floating-ui/dom": "1.8.0",
         "@modelcontextprotocol/sdk": "^1.32.1",
         "@moduletrace/bun-sqlite": "^1.3.0",
         "@moduletrace/bunext": "^1.3.3",
         "@moduletrace/twui": "^0.1.2",
+        "@tiptap/extension-bubble-menu": "3.32.0",
+        "@tiptap/extension-mention": "3.32.0",
+        "@tiptap/extension-placeholder": "3.32.0",
+        "@tiptap/markdown": "3.32.0",
+        "@tiptap/pm": "3.32.0",
+        "@tiptap/react": "3.32.0",
+        "@tiptap/starter-kit": "3.32.0",
         "ace-builds": "^1.44.0",
         "dayjs": "^1.11.23",
         "gray-matter": "^4.0.3",
@@ -56,14 +64,19 @@
         "react-markdown": "^10.1.0",
         "react-responsive-modal": "^7.2.0",
         "rehype-prism-plus": "^2.0.2",
+        "remark-breaks": "4.0.0",
         "remark-gfm": "^4.0.1",
         "sanitize-html": "^2.18.1",
         "sharp": "^0.35.3",
         "tailwind-merge": "^3.6.0",
         "turndown": "^7.2.4",
         "unpdf": "^1.8.0",
+        "use-sync-external-store": "file:./packages/use-sync-external-store-esm",
         "web-push": "^3.6.7",
         "xlsx": "^0.18.5",
         "zod": "4.1.12"
+    },
+    "overrides": {
+        "use-sync-external-store": "file:./packages/use-sync-external-store-esm"
     }
 }