Phase 6: Permissions, Push, WebAuthn scaffolding

Backend:
- internal/permissions/permissions.go: permission bitflags (VIEW_CHANNEL through SHARE_SCREEN)
- internal/permissions/checker.go: permission checker with role aggregation
- internal/middleware/permission.go: RequirePermission middleware
- internal/push/handlers.go: push subscription CRUD, VAPID key endpoint, SendPush
- internal/auth/webauthn.go: WebAuthn passkey scaffolding (begin/finish endpoints)
- internal/db/db.go: is_default on roles, push_subscriptions table, webauthn_credentials table
- go.mod: added webpush-go, go-webauthn dependencies

Frontend:
- stores/role.ts: Zustand store for role management
- RoleManager.tsx: role CRUD with permission checkboxes
- MemberRoleAssign.tsx: assign roles to members
- App.tsx: /servers/:serverId/roles route

web/src/App.tsx

@@ -5,6 +5,7 @@ import { ChatArea } from './components/ChatArea.tsx';
 import { UserSettings } from './components/UserSettings.tsx';
 import { BotManager } from './components/BotManager.tsx';
 import { CommandManager } from './components/CommandManager.tsx';
+import { RoleManager } from './components/RoleManager.tsx';
 import { useAuthStore } from './stores/auth.ts';
 
 function ProtectedRoute({ children }: { children: React.ReactNode }) {
@@ -71,6 +72,24 @@ function App() {
             </ProtectedRoute>
           }
         />
+        <Route
+          path="/servers/:serverId/roles"
+          element={
+            <ProtectedRoute>
+              <div className="h-full w-full flex flex-col bg-gb-bg">
+                <header className="flex items-center gap-4 px-4 py-2 border-b border-gb-bg-t bg-gb-bg-s">
+                  <Link to="/" className="text-gb-fg-f hover:text-gb-aqua font-mono text-sm">
+                    ← [BACK]
+                  </Link>
+                  <span className="text-gb-orange font-mono text-sm">ROLE MANAGER</span>
+                </header>
+                <div className="flex-1 overflow-hidden">
+                  <RoleManager />
+                </div>
+              </div>
+            </ProtectedRoute>
+          }
+        />
         <Route
           path="/"
           element={