fix: permissions matrix UI now returns proper shape from backend

The frontend admin.js expects {sets, users, permissions} but
ListPermissions returned a flat []SetPermission slice.

- Add PermissionsMatrix struct with JSON tags
- Update AdminService.ListPermissions to return *PermissionsMatrix
- Update mocks and all call sites to match new signature
- Update tests to assert the new matrix shape

2 files changed, 2 insertions, 2 deletions

diff --git a/internal/api/handlers_more_test.go b/internal/api/handlers_more_test.go
index 13c57cf..b162fa8 100644
--- a/internal/api/handlers_more_test.go
+++ b/internal/api/handlers_more_test.go
@@ -1583,7 +1583,7 @@ func TestServer_AdminListPermissions(t *testing.T) {
 			var as service.AdminService
 			if !tt.svcNil {
 				as = &service.MockAdminService{
-					ListPermissionsFunc: func(ctx context.Context) ([]model.SetPermission, error) { return nil, tt.svcErr },
+					ListPermissionsFunc: func(ctx context.Context) (*service.PermissionsMatrix, error) { return nil, tt.svcErr },
 				}
 			}
 			srv := newTestServer(t, store, nil, sm, cfg, nil, as, nil, nil)
diff --git a/internal/api/handlers_test.go b/internal/api/handlers_test.go
index e65b854..b5ca9c7 100644
--- a/internal/api/handlers_test.go
+++ b/internal/api/handlers_test.go
@@ -1148,7 +1148,7 @@ func TestServer_AdminRoutes(t *testing.T) {
 			return &model.User{ID: 2, Username: username, IsAdmin: isAdmin}, nil
 		},
 		DeleteUserFunc:       func(ctx context.Context, id int64) error { return nil },
-		ListPermissionsFunc:  func(ctx context.Context) ([]model.SetPermission, error) { return nil, nil },
+		ListPermissionsFunc:  func(ctx context.Context) (*service.PermissionsMatrix, error) { return nil, nil },
 		GrantPermissionFunc:  func(ctx context.Context, setID, userID int64, role model.Role) error { return nil },
 		RevokePermissionFunc: func(ctx context.Context, setID, userID int64) error { return nil },
 	}