feat(ui): hybrid sidebar (sectioned + active pill + agent dots) + agent profile viewer in Settings

Sidebar: Spaces / Agents / Navigate sections, accent pill on active item, status
dots on agents. Settings Agents rows expand to show the agent's persona (soul) +
capabilities/scopes via GET /api/agents/:id/profile.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

public/components/sidebar.js

@@ -19,6 +19,7 @@ function navItem(label, hash, opts = {}) {
     },
     opts.icon ? el('span', { class: 'caret' }, opts.icon) : null,
     el('span', { style: { flex: 1 } }, label),
+    opts.dot ? el('span', { class: 'sb-dot ' + opts.dot }) : null,
     opts.badge !== undefined && opts.badge !== null ? el('span', { class: 'badge' }, String(opts.badge)) : null
   );
 }
@@ -87,12 +88,14 @@ export function renderSidebar(root) {
       el('div', { class: 'sb-title' }, 'Spaces'),
       spacesContainer
     ),
-    el('hr'),
+    el('div', { class: 'sb-section' },
+      el('div', { class: 'sb-title' }, 'Agents'),
+      navItem('Sentinel', '/sentinel', { dot: 'ok' }),
+      navItem('Little Blue', '/little-blue', { dot: 'lb' })
+    ),
     el('div', { class: 'sb-section' },
       el('div', { class: 'sb-title' }, 'Navigate'),
       navItem('Sacred Valley', '/sacred-valley'),
-      navItem('Sentinel', '/sentinel'),
-      navItem('Little Blue', '/little-blue'),
       navItem('Terminal', '/terminal'),
       navItem('Search', '/search'),
       inboxItem,