feat(vscode-ide-companion): 增加代码编辑功能和文件操作支持

- 实现了与 Claude Code 类似的代码编辑功能
- 添加了文件打开、保存等操作的支持
- 优化了消息显示，增加了代码高亮和文件路径点击功能
- 改进了用户界面，增加了编辑模式切换和思考模式功能

packages/vscode-ide-companion/src/webview/ClaudeCodeStyles.css

@@ -369,6 +369,64 @@
   font-size: 0.85em;
 }
 
+/* Code content wrapper for better scrolling */
+.code-content {
+  max-height: 300px;
+  overflow-y: auto;
+  display: block;
+}
+
+/* Diff display container */
+.diff-display-container {
+  width: 100%;
+  display: flex;
+  flex-direction: column;
+  gap: 8px;
+}
+
+.diff-header {
+  display: flex;
+  justify-content: space-between;
+  align-items: center;
+  padding-bottom: 4px;
+  border-bottom: 1px solid var(--app-primary-border-color);
+}
+
+.diff-file-path {
+  font-weight: 500;
+  color: var(--app-secondary-foreground);
+}
+
+.open-diff-button {
+  display: inline-flex;
+  align-items: center;
+  gap: 4px;
+  padding: 4px 8px;
+  background: var(--app-ghost-button-hover-background);
+  border: none;
+  border-radius: 4px;
+  cursor: pointer;
+  font-size: 0.85em;
+  color: var(--app-secondary-foreground);
+}
+
+.open-diff-button:hover {
+  background: var(--vscode-button-hoverBackground);
+  color: var(--vscode-button-foreground);
+}
+
+.diff-section {
+  display: flex;
+  flex-direction: column;
+  gap: 4px;
+}
+
+.diff-label {
+  font-weight: 500;
+  color: var(--app-secondary-foreground);
+  font-size: 0.85em;
+}
+
 /* Status indicators for tool calls */
 .tool-call-status-indicator {
   display: inline-flex;