feat: refactor role system to is_admin flag, add Badge component, fix native dialogs

- Separate admin identity from role: viewer|model + is_admin boolean flag
- DB migration 0001_is_admin: adds column, migrates former admin role users
- Update ACL helpers, auth session, GraphQL types and all resolvers
- Admin layout guard and header links check is_admin instead of role
- Admin users table: show Admin badge next to name, remove admin from role select
- Admin user edit page: is_admin checkbox toggle
- Install shadcn Badge component; use in admin users table
- Fix duplicate photo keys in adminGetUser resolver
- Replace confirm() in /me recordings with Dialog component

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

packages/frontend/src/lib/services.ts

@@ -62,6 +62,7 @@ const ME_QUERY = gql`
       description
       tags
       role
+      is_admin
       avatar
       banner
       email_verified
@@ -1022,6 +1023,7 @@ const ADMIN_LIST_USERS_QUERY = gql`
         artist_name
         slug
         role
+        is_admin
         avatar
         email_verified
         date_created
@@ -1052,6 +1054,7 @@ const ADMIN_UPDATE_USER_MUTATION = gql`
   mutation AdminUpdateUser(
     $userId: String!
     $role: String
+    $isAdmin: Boolean
     $firstName: String
     $lastName: String
     $artistName: String
@@ -1061,6 +1064,7 @@ const ADMIN_UPDATE_USER_MUTATION = gql`
     adminUpdateUser(
       userId: $userId
       role: $role
+      isAdmin: $isAdmin
       firstName: $firstName
       lastName: $lastName
       artistName: $artistName
@@ -1073,6 +1077,7 @@ const ADMIN_UPDATE_USER_MUTATION = gql`
       last_name
       artist_name
       role
+      is_admin
       avatar
       banner
       date_created
@@ -1083,6 +1088,7 @@ const ADMIN_UPDATE_USER_MUTATION = gql`
 export async function adminUpdateUser(input: {
   userId: string;
   role?: string;
+  isAdmin?: boolean;
   firstName?: string;
   lastName?: string;
   artistName?: string;
@@ -1128,6 +1134,7 @@ const ADMIN_GET_USER_QUERY = gql`
       artist_name
       slug
       role
+      is_admin
       avatar
       banner
       description