feat(ui): onboarding wizard, comment thread, markdown editor, and UX polish

Refactor onboarding wizard with ASCII art animation and expanded adapter
support. Enhance markdown editor with code block, table, and CodeMirror
plugins. Improve comment thread layout. Add activity charts to agent
detail page. Polish metric cards, issue detail reassignment, and new
issue dialog. Simplify agent detail page structure.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ui/src/components/MarkdownEditor.tsx

@@ -10,6 +10,8 @@ import {
 } from "react";
 import {
   MDXEditor,
+  codeBlockPlugin,
+  codeMirrorPlugin,
   type MDXEditorMethods,
   headingsPlugin,
   imagePlugin,
@@ -18,6 +20,7 @@ import {
   listsPlugin,
   markdownShortcutPlugin,
   quotePlugin,
+  tablePlugin,
   thematicBreakPlugin,
   type RealmPlugin,
 } from "@mdxeditor/editor";
@@ -62,6 +65,26 @@ interface MentionState {
   endPos: number;
 }
 
+const CODE_BLOCK_LANGUAGES: Record<string, string> = {
+  txt: "Text",
+  md: "Markdown",
+  js: "JavaScript",
+  jsx: "JavaScript (JSX)",
+  ts: "TypeScript",
+  tsx: "TypeScript (TSX)",
+  json: "JSON",
+  bash: "Bash",
+  sh: "Shell",
+  python: "Python",
+  go: "Go",
+  rust: "Rust",
+  sql: "SQL",
+  html: "HTML",
+  css: "CSS",
+  yaml: "YAML",
+  yml: "YAML",
+};
+
 function detectMention(container: HTMLElement): MentionState | null {
   const sel = window.getSelection();
   if (!sel || sel.rangeCount === 0 || !sel.isCollapsed) return null;
@@ -174,9 +197,12 @@ export const MarkdownEditor = forwardRef<MarkdownEditorRef, MarkdownEditorProps>
       headingsPlugin(),
       listsPlugin(),
       quotePlugin(),
+      tablePlugin(),
       linkPlugin(),
       linkDialogPlugin(),
       thematicBreakPlugin(),
+      codeBlockPlugin(),
+      codeMirrorPlugin({ codeBlockLanguages: CODE_BLOCK_LANGUAGES }),
       markdownShortcutPlugin(),
     ];
     if (imageHandler) {