fix: address PR feedback for user API improvements

- Apply detached entity re-fetch pattern to updateUserAccount for
  consistency with updatePassword endpoint
- Change hardcoded "User not found" error to use i18n getMessage()
  with fallback for consistency with other error messages
- Update test mocks to use 4-argument getMessage() signature that
  includes default message parameter
- Add findUserByEmail mocks to updateUser and updatePassword tests

Author: devondragon

src/main/java/com/digitalsanctuary/spring/user/api/UserAPI.java

@@ -155,7 +155,12 @@ public ResponseEntity<JSONResponse> updateUserAccount(@AuthenticationPrincipal D
 			@Valid @RequestBody UserProfileUpdateDto profileUpdateDto,
 			HttpServletRequest request, Locale locale) {
 		validateAuthenticatedUser(userDetails);
-		User user = userDetails.getUser();
+		// Re-fetch user from database to ensure we have an attached entity
+		User user = userService.findUserByEmail(userDetails.getUser().getEmail());
+		if (user == null) {
+			log.error("User not found in database: {}", userDetails.getUser().getEmail());
+			return buildErrorResponse(messages.getMessage("message.user.not-found", null, "User not found", locale), 1, HttpStatus.BAD_REQUEST);
+		}
 		user.setFirstName(profileUpdateDto.getFirstName());
 		user.setLastName(profileUpdateDto.getLastName());
 		userService.saveRegisteredUser(user);
@@ -276,7 +281,7 @@ public ResponseEntity<JSONResponse> updatePassword(@AuthenticationPrincipal DSUs
 		User user = userService.findUserByEmail(userDetails.getUser().getEmail());
 		if (user == null) {
 			log.error("User not found in database: {}", userDetails.getUser().getEmail());
-			return buildErrorResponse("User not found", 1, HttpStatus.BAD_REQUEST);
+			return buildErrorResponse(messages.getMessage("message.user.not-found", null, "User not found", locale), 1, HttpStatus.BAD_REQUEST);
 		}
 
 		try {

src/test/java/com/digitalsanctuary/spring/user/api/UserAPIUnitTest.java

@@ -400,7 +400,8 @@ public Object resolveArgument(org.springframework.core.MethodParameter parameter
                     .setControllerAdvice(new TestExceptionHandler())
                     .build();
 
-            when(messageSource.getMessage(eq("message.update-password.success"), any(), any(Locale.class)))
+            when(userService.findUserByEmail(testUser.getEmail())).thenReturn(testUser);
+            when(messageSource.getMessage(eq("message.update-password.success"), any(), any(), any(Locale.class)))
                     .thenReturn("Password updated successfully");
             when(userService.checkIfValidOldPassword(any(User.class), eq("oldPassword"))).thenReturn(true);
 
@@ -443,7 +444,8 @@ public Object resolveArgument(org.springframework.core.MethodParameter parameter
                     .setControllerAdvice(new TestExceptionHandler())
                     .build();
 
-            when(messageSource.getMessage(eq("message.update-password.invalid-old"), any(), any(Locale.class)))
+            when(userService.findUserByEmail(testUser.getEmail())).thenReturn(testUser);
+            when(messageSource.getMessage(eq("message.update-password.invalid-old"), any(), any(), any(Locale.class)))
                     .thenReturn("Invalid old password");
             when(userService.checkIfValidOldPassword(any(User.class), eq("wrongPassword"))).thenReturn(false);
 
@@ -509,7 +511,8 @@ public Object resolveArgument(org.springframework.core.MethodParameter parameter
                     .setControllerAdvice(new TestExceptionHandler())
                     .build();
 
-            when(messageSource.getMessage(eq("message.update-user.success"), any(), any(Locale.class)))
+            when(userService.findUserByEmail(testUser.getEmail())).thenReturn(testUser);
+            when(messageSource.getMessage(eq("message.update-user.success"), any(), any(), any(Locale.class)))
                     .thenReturn("Profile updated successfully");
             when(userService.saveRegisteredUser(any(User.class))).thenReturn(testUser);
 
@@ -522,8 +525,8 @@ public Object resolveArgument(org.springframework.core.MethodParameter parameter
                     .andExpect(jsonPath("$.success").value(true))
                     .andExpect(jsonPath("$.messages[0]").value("Profile updated successfully"));
 
-            verify(userService).saveRegisteredUser(argThat(user -> 
-                user.getFirstName().equals("UpdatedFirst") && 
+            verify(userService).saveRegisteredUser(argThat(user ->
+                user.getFirstName().equals("UpdatedFirst") &&
                 user.getLastName().equals("UpdatedLast")
             ));
         }
@@ -741,7 +744,8 @@ public Object resolveArgument(org.springframework.core.MethodParameter parameter
                     .setControllerAdvice(new TestExceptionHandler())
                     .build();
 
-            when(messageSource.getMessage(eq("message.update-user.success"), any(), any(Locale.class)))
+            when(userService.findUserByEmail(testUser.getEmail())).thenReturn(testUser);
+            when(messageSource.getMessage(eq("message.update-user.success"), any(), any(), any(Locale.class)))
                     .thenReturn("Profile updated successfully");
             when(userService.saveRegisteredUser(any(User.class))).thenReturn(testUser);