feat: UI separates locals, remotes, and virtuals (#54)

## Summary
- New "Locals" sidebar nav item with list + detail + browse pages
- Remotes page filters out local repos (repo_type=local hidden)
- LocalDetail: simplified view — just name, type, description + "Browse Files" button
- Virtuals: member links resolve to /locals/ or /remotes/ based on repo_type
- Objects page detects context for correct back-navigation

## Test plan
- [ ] Visual check: locals page shows only local repos
- [ ] Remotes page hides local repos
- [ ] Virtual member links point to correct pages
- [ ] Browse files works from local detail page

Reviewed-on: #54
Co-authored-by: Ben Vincent <ben@unkin.net>
Co-committed-by: Ben Vincent <ben@unkin.net>

ui/src/App.tsx

@@ -2,6 +2,8 @@ import { Routes, Route, NavLink } from 'react-router-dom';
 import { Dashboard } from './pages/Dashboard';
 import { Remotes } from './pages/Remotes';
 import { RemoteDetail } from './pages/RemoteDetail';
+import { Locals } from './pages/Locals';
+import { LocalDetail } from './pages/LocalDetail';
 import { Virtuals } from './pages/Virtuals';
 import { Objects } from './pages/Objects';
 import { Probe } from './pages/Probe';
@@ -18,6 +20,7 @@ export function App() {
         <div className="sidebar-nav">
           <NavLink to="/" end>Dashboard</NavLink>
           <NavLink to="/remotes">Remotes</NavLink>
+          <NavLink to="/locals">Locals</NavLink>
           <NavLink to="/virtuals">Virtuals</NavLink>
           <NavLink to="/probe">Test Remote</NavLink>
         </div>
@@ -31,6 +34,9 @@ export function App() {
           <Route path="/remotes" element={<Remotes />} />
           <Route path="/remotes/:name" element={<RemoteDetail />} />
           <Route path="/remotes/:name/objects" element={<Objects />} />
+          <Route path="/locals" element={<Locals />} />
+          <Route path="/locals/:name" element={<LocalDetail />} />
+          <Route path="/locals/:name/objects" element={<Objects />} />
           <Route path="/virtuals" element={<Virtuals />} />
           <Route path="/probe" element={<Probe />} />
         </Routes>