feat(ui): render markdown in peek pane

- Add marked.js for full markdown rendering
- Stream peek body renders as markdown
- Card peek non-code content renders as markdown
- Code/snippet cards keep escaped pre/code display
- Styled: headers, lists, blockquotes, inline code, code blocks, links, hr
- Graceful fallback to escHtml if marked fails to load

web/style.css

@@ -877,6 +877,85 @@ kbd { background: var(--raised); border: 1px solid var(--border); border-radius:
 
 .peek-body:hover { background: var(--raised); }
 
+.peek-body.md {
+    font-family: var(--sans);
+    font-size: 13px;
+    line-height: 1.65;
+    white-space: normal;
+}
+
+.peek-body.md h1, .peek-body.md h2, .peek-body.md h3,
+.peek-body.md h4, .peek-body.md h5, .peek-body.md h6 {
+    font-weight: 600;
+    color: var(--text);
+    margin: 14px 0 6px;
+    line-height: 1.3;
+}
+
+.peek-body.md h1 { font-size: 17px; }
+.peek-body.md h2 { font-size: 15px; }
+.peek-body.md h3 { font-size: 14px; }
+
+.peek-body.md p { margin: 0 0 10px; }
+.peek-body.md p:last-child { margin-bottom: 0; }
+
+.peek-body.md ul, .peek-body.md ol {
+    padding-left: 20px;
+    margin: 0 0 10px;
+}
+
+.peek-body.md li { margin-bottom: 3px; }
+
+.peek-body.md blockquote {
+    border-left: 2px solid var(--accent);
+    padding-left: 12px;
+    color: var(--muted);
+    margin: 0 0 10px;
+}
+
+.peek-body.md code {
+    font-family: var(--mono);
+    font-size: 11px;
+    background: var(--bg);
+    border: 1px solid var(--border);
+    border-radius: var(--r1);
+    padding: 1px 5px;
+}
+
+.peek-body.md pre {
+    background: var(--bg);
+    border: 1px solid var(--border);
+    border-radius: var(--r2);
+    padding: 10px 12px;
+    overflow-x: auto;
+    margin: 0 0 10px;
+}
+
+.peek-body.md pre code {
+    background: none;
+    border: none;
+    padding: 0;
+    font-size: 11px;
+    line-height: 1.6;
+}
+
+.peek-body.md a {
+    color: var(--event);
+    text-decoration: none;
+    border-bottom: 1px solid rgba(104,152,200,.3);
+}
+
+.peek-body.md a:hover { border-bottom-color: var(--event); }
+
+.peek-body.md strong { font-weight: 600; }
+.peek-body.md em { font-style: italic; color: var(--muted); }
+
+.peek-body.md hr {
+    border: none;
+    border-top: 1px solid var(--border);
+    margin: 14px 0;
+}
+
 .peek-meta {
     display: flex;
     align-items: center;