feat(ui): add keyboard shortcuts for AI profiles navigation

- Add M shortcut to navigate to AI Profiles from sidebar
- Add N shortcut to create new profile in profiles view
- Display keyboard shortcut indicators in UI

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4 <noreply@anthropic.com>

app/src/components/layout/sidebar.tsx

@@ -489,6 +489,7 @@ export function Sidebar() {
           id: "profiles",
           label: "AI Profiles",
           icon: UserCircle,
+          shortcut: NAV_SHORTCUTS.profiles,
         },
       ],
     },