fix(services): Fix service startup failures

- Remove duplicate CoreModule() calls from all service main.go files
  - NewContainer() already includes CoreModule() automatically
  - This was causing duplicate ConfigProvider provider errors

- Update all _fx.go files to use *database.Client instead of *ent.Client
  - database.Client embeds *ent.Client, so it can be used directly
  - This fixes type mismatches between providers and consumers
  - Keep ent import for constants like ent.Desc

- All services now build and should start successfully

cmd/auth-service/main.go

@@ -81,10 +81,8 @@ func (s *grpcServerWrapper) Port() int {
 
 func main() {
 	// Create DI container
+	// Note: CoreModule() is automatically included by NewContainer()
 	container := di.NewContainer(
-		// Core kernel services
-		di.CoreModule(),
-
 		// Database for auth service (auth schema)
 		fx.Provide(func(cfg config.ConfigProvider, log logger.Logger) (*database.Client, error) {
 			dsn := cfg.GetString("database.dsn")