refactor: streaming download, Git LFS templates, deploy workflow

- Replace base64 JSON response with StreamingResponseBody (zero-buffer)
- Error responses return JSON via GlobalExceptionHandler (400/404)
- Add git-lfs track for *.docx to keep repo lean
- Add deploy/deploy.sh: one-click build + restart
- Add deploy/clean-lfs.sh: periodic LFS cache cleanup
- Add deploy/gmp-service.service: systemd service unit
- Remove unused ApiResponse and DocxExportData DTOs
- Fix build.sh/run.sh jar name (gmp-mock-service -> gmp-service)
- Add TemplateNotFoundException for missing templates

src/main/java/com/gmp/mock/handler/GlobalExceptionHandler.java

@@ -1,5 +1,6 @@
 package com.gmp.mock.handler;
 
+import java.util.Map;
 import java.util.stream.Collectors;
 
 import org.springframework.http.ResponseEntity;
@@ -7,16 +8,23 @@ import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.annotation.ExceptionHandler;
 import org.springframework.web.bind.annotation.RestControllerAdvice;
 
-import com.gmp.mock.dto.ApiResponse;
+import com.gmp.mock.service.TemplateNotFoundException;
 
 @RestControllerAdvice
 public class GlobalExceptionHandler {
 
     @ExceptionHandler(MethodArgumentNotValidException.class)
-    public ResponseEntity<ApiResponse<Void>> handleValidation(MethodArgumentNotValidException ex) {
+    public ResponseEntity<Map<String, Object>> handleValidation(MethodArgumentNotValidException ex) {
         String message = ex.getBindingResult().getFieldErrors().stream()
                 .map(e -> e.getDefaultMessage())
                 .collect(Collectors.joining("; "));
-        return ResponseEntity.ok(ApiResponse.error(400, message));
+        return ResponseEntity.badRequest()
+                .body(Map.of("code", 400, "msg", message));
+    }
+
+    @ExceptionHandler(TemplateNotFoundException.class)
+    public ResponseEntity<Map<String, Object>> handleTemplateNotFound(TemplateNotFoundException ex) {
+        return ResponseEntity.status(404)
+                .body(Map.of("code", 404, "msg", ex.getMessage()));
     }
 }