feat(HAI-003): render task descriptions as markdown in dashboard

- Add react-markdown and remark-gfm dependencies
- Replace pre element with ReactMarkdown in TaskDetailModal
- Add markdown prose styles optimized for dark theme
- Regenerate pnpm-lock.yaml to resolve merge conflicts

packages/dashboard/app/components/TaskDetailModal.tsx

@@ -1,4 +1,6 @@
 import { useCallback, useEffect } from "react";
+import ReactMarkdown from "react-markdown";
+import remarkGfm from "remark-gfm";
 import type { Task, TaskDetail, Column, MergeResult } from "@hai/core";
 import { COLUMN_LABELS, VALID_TRANSITIONS } from "@hai/core";
 import type { ToastType } from "../hooks/useToast";
@@ -97,7 +99,15 @@ export function TaskDetailModal({
           </div>
           <div className="detail-section">
             <h4>PROMPT.md</h4>
-            <pre className="detail-prompt">{task.prompt || "(no prompt)"}</pre>
+            {task.prompt ? (
+              <div className="detail-prompt markdown-body">
+                <ReactMarkdown remarkPlugins={[remarkGfm]}>
+                  {task.prompt}
+                </ReactMarkdown>
+              </div>
+            ) : (
+              <div className="detail-prompt">(no prompt)</div>
+            )}
           </div>
           {task.dependencies && task.dependencies.length > 0 && (
             <div className="detail-deps">

packages/dashboard/app/styles.css

@@ -399,6 +399,116 @@ html, body {
   overflow-y: auto;
 }
 
+.detail-prompt.markdown-body {
+  font-family: inherit;
+  white-space: normal;
+  color: var(--text);
+}
+
+/* === Markdown Prose === */
+.markdown-body h1,
+.markdown-body h2,
+.markdown-body h3,
+.markdown-body h4 {
+  color: var(--text);
+  font-weight: 600;
+  margin-top: 1.2em;
+  margin-bottom: 0.5em;
+  line-height: 1.3;
+}
+.markdown-body h1 { font-size: 1.4em; border-bottom: 1px solid var(--border); padding-bottom: 0.3em; }
+.markdown-body h2 { font-size: 1.2em; border-bottom: 1px solid var(--border); padding-bottom: 0.3em; }
+.markdown-body h3 { font-size: 1.05em; }
+.markdown-body h4 { font-size: 1em; color: var(--text-muted); }
+.markdown-body h1:first-child,
+.markdown-body h2:first-child,
+.markdown-body h3:first-child,
+.markdown-body h4:first-child { margin-top: 0; }
+
+.markdown-body p {
+  margin: 0.6em 0;
+}
+
+.markdown-body ul,
+.markdown-body ol {
+  padding-left: 1.6em;
+  margin: 0.5em 0;
+}
+.markdown-body ul { list-style: disc; }
+.markdown-body ol { list-style: decimal; }
+.markdown-body li { margin: 0.25em 0; }
+.markdown-body li > ul,
+.markdown-body li > ol { margin: 0.15em 0; }
+
+.markdown-body code {
+  background: var(--card);
+  border-radius: 4px;
+  padding: 0.15em 0.4em;
+  font-size: 0.9em;
+  font-family: "SF Mono", Monaco, Consolas, monospace;
+}
+
+.markdown-body pre {
+  background: var(--card);
+  border: 1px solid var(--border);
+  border-radius: var(--radius);
+  padding: 12px;
+  overflow-x: auto;
+  margin: 0.6em 0;
+}
+.markdown-body pre > code {
+  background: none;
+  padding: 0;
+  border-radius: 0;
+  font-size: 0.85em;
+}
+
+.markdown-body a {
+  color: var(--todo);
+  text-decoration: none;
+}
+.markdown-body a:hover { text-decoration: underline; }
+
+.markdown-body blockquote {
+  border-left: 3px solid var(--border);
+  padding: 0.3em 0.8em;
+  margin: 0.6em 0;
+  color: var(--text-muted);
+}
+
+.markdown-body table {
+  border-collapse: collapse;
+  width: 100%;
+  margin: 0.6em 0;
+  font-size: 0.9em;
+}
+.markdown-body th,
+.markdown-body td {
+  border: 1px solid var(--border);
+  padding: 6px 10px;
+  text-align: left;
+}
+.markdown-body th {
+  background: var(--card);
+  font-weight: 600;
+}
+
+.markdown-body input[type="checkbox"] {
+  margin-right: 0.4em;
+  vertical-align: middle;
+}
+
+.markdown-body hr {
+  border: none;
+  border-top: 1px solid var(--border);
+  margin: 1em 0;
+}
+
+.markdown-body strong { color: var(--text); }
+.markdown-body em { font-style: italic; }
+
+.markdown-body img { max-width: 100%; border-radius: var(--radius); }
+
 .detail-deps { margin-top: 16px; }
 .detail-deps h4 {
   font-size: 12px;

packages/dashboard/package.json

@@ -16,7 +16,9 @@
     "express": "^5.1.0",
     "lucide-react": "^1.7.0",
     "react": "^19.0.0",
-    "react-dom": "^19.0.0"
+    "react-dom": "^19.0.0",
+    "react-markdown": "^10.1.0",
+    "remark-gfm": "^4.0.1"
   },
   "devDependencies": {
     "@types/express": "^5.0.0",