feat(vscode-ide-companion): 新增上下文附件管理功能

- 新增 ContextAttachmentManager 管理上下文附件
- 新增 ContextPills 组件用于显示上下文标签
- 支持文件、符号、选区等多种上下文类型

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

packages/vscode-ide-companion/src/webview/ContextAttachmentManager.ts

@@ -0,0 +1,97 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/**
+ * Context attachment types
+ * Based on vscode-copilot-chat implementation
+ */
+export interface ContextAttachment {
+  id: string;
+  type: 'file' | 'symbol' | 'selection' | 'variable';
+  name: string;
+  value: string | { uri: string; range?: { start: number; end: number } };
+  icon?: string;
+}
+
+/**
+ * Manages context attachments for the chat
+ * Similar to ChatContextAttachments in vscode-copilot-chat
+ */
+export class ContextAttachmentManager {
+  private attachments: Map<string, ContextAttachment> = new Map();
+  private listeners: Array<(attachments: ContextAttachment[]) => void> = [];
+
+  /**
+   * Add a context attachment
+   */
+  addAttachment(attachment: ContextAttachment): void {
+    this.attachments.set(attachment.id, attachment);
+    this.notifyListeners();
+  }
+
+  /**
+   * Remove a context attachment
+   */
+  removeAttachment(id: string): void {
+    this.attachments.delete(id);
+    this.notifyListeners();
+  }
+
+  /**
+   * Get all attachments
+   */
+  getAttachments(): ContextAttachment[] {
+    return Array.from(this.attachments.values());
+  }
+
+  /**
+   * Check if an attachment exists
+   */
+  hasAttachment(id: string): boolean {
+    return this.attachments.has(id);
+  }
+
+  /**
+   * Clear all attachments
+   */
+  clearAttachments(): void {
+    this.attachments.clear();
+    this.notifyListeners();
+  }
+
+  /**
+   * Subscribe to attachment changes
+   */
+  subscribe(listener: (attachments: ContextAttachment[]) => void): () => void {
+    this.listeners.push(listener);
+    return () => {
+      const index = this.listeners.indexOf(listener);
+      if (index > -1) {
+        this.listeners.splice(index, 1);
+      }
+    };
+  }
+
+  /**
+   * Notify all listeners of changes
+   */
+  private notifyListeners(): void {
+    const attachments = this.getAttachments();
+    this.listeners.forEach((listener) => listener(attachments));
+  }
+
+  /**
+   * Get context for message sending
+   */
+  getContextForMessage(): Array<Record<string, unknown>> {
+    return this.getAttachments().map((att) => ({
+      id: att.id,
+      type: att.type,
+      name: att.name,
+      value: att.value,
+    }));
+  }
+}