fix(macos): Fix image attachment not displaying in chat input

## Problem
When users selected images on macOS, the file path did not appear
in the chat input field due to:

1. **Duplicate case statement** (script.ts:2099-2106)
   - JavaScript switch had two 'imagePath' cases
   - Only the last matching case executes
   - First (correct) handler was never executed

2. **Data structure mismatch** (extension.ts:1956-1959)
   - Backend sent: {type: 'imagePath', path: '/path'}
   - Frontend expected: {type: 'imagePath', data: {filePath: '/path'}}
   - Frontend couldn't find the data → silent failure

## Solution
- **Removed duplicate case statement** in script.ts
  - Deleted lines 2099-2106
  - Only correct handler (lines 1979-2006) remains

- **Unified data structure** in extension.ts
  - Changed to send {data: {filePath}} format
  - Matches frontend expectation
  - Consistent with other message types

## Testing
Tested in Extension Development Host (F5):
- ✅ Click image button → Finder opens
- ✅ Select single image → Path appears in chat input
- ✅ Select multiple images → All paths appear
- ✅ Cancel selection → No errors

## Impact
- **Users**: macOS users can now attach images successfully
- **Code Quality**: Removed code duplication, unified data structure
- **Compatibility**: No breaking changes

## Files Changed
- src/script.ts: Remove duplicate case (-11 lines)
- src/extension.ts: Fix data structure (+4, -1 lines)

Author: doscode-kr

src/extension.ts

@@ -1955,7 +1955,9 @@ class ClaudeChatProvider {
 				result.forEach(uri => {
 					this._postMessage({
 						type: 'imagePath',
-						path: uri.fsPath
+						data: {
+							filePath: uri.fsPath
+						}
 					});
 				});
 			}

src/script.ts

@@ -2070,16 +2070,7 @@ const getScript = (isTelemetryEnabled: boolean) => `<script>
 					selectedFileIndex = -1;
 					renderFileList();
 					break;
-					
-				case 'imagePath':
-					// Add the image path to the textarea
-					const currentText = messageInput.value;
-					const pathIndicator = \`@\${message.path} \`;
-					messageInput.value = currentText + pathIndicator;
-					messageInput.focus();
-					adjustTextareaHeight();
-					break;
-					
+
 				case 'conversationList':
 					displayConversationList(message.data);
 					break;