feat: API key management improvements

- Rename routes: /dashboard/tokens → /dashboard/apikeys, /dashboard/manager/keys → /dashboard/manager/channels
- Add KeyPlain field to store plaintext API keys for re-viewing
- API key list shows masked key (sk-ot-123456****abcd) with eye toggle to reveal
- Copy button with 2s feedback on key list
- TokenNew shows full key + copy after creation
- Increase key prefix display to 12 characters
- Fix SQLite driver: replace gorm.io/driver/sqlite with ncruces/go-sqlite3/gormlite
- Fix user.status === 'active' checks across frontend views
- Add channel store for new channels API
- Update Makefile frontend build to work reliably

BREAKING CHANGE: Existing API keys created before this change will not show their plaintext value (only prefix visible).

frontend/src/router/index.ts

@@ -8,7 +8,8 @@ const router = createRouter({
 
 router.beforeEach((to, from, next) => {
   const isAuthenticated = localStorage.getItem('token')
-  if (to.meta.requiresAuth && !isAuthenticated) {
+  const requiresAuth = to.matched.some(record => record.meta.requiresAuth)
+  if (requiresAuth && !isAuthenticated) {
     next('/login')
   } else {
     next()