refactor(vscode-ide-companion): 重构 WebViewProvider 初始化逻辑

- 抽离初始化代理连接逻辑到单独的方法中
- 优化面板恢复时的代理连接流程
- 移除 EmptyState 组件中的信息横幅
- 在 App 组件中添加可关闭的信息横幅
- 调整输入表单样式，移除冗余样式

packages/vscode-ide-companion/src/webview/utils/resourceUrl.ts

@@ -0,0 +1,74 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+// Extend Window interface to include __EXTENSION_URI__
+declare global {
+  interface Window {
+    __EXTENSION_URI__?: string;
+  }
+}
+
+/**
+ * Get the extension URI from the body data attribute or window global
+ * @returns Extension URI or undefined if not found
+ */
+function getExtensionUri(): string | undefined {
+  // First try to get from window (for backwards compatibility)
+  if (window.__EXTENSION_URI__) {
+    return window.__EXTENSION_URI__;
+  }
+
+  // Then try to get from body data attribute (CSP-compliant method)
+  const bodyUri = document.body?.getAttribute('data-extension-uri');
+  if (bodyUri) {
+    // Cache it in window for future use
+    window.__EXTENSION_URI__ = bodyUri;
+    return bodyUri;
+  }
+
+  return undefined;
+}
+
+/**
+ * Generate a resource URL for webview access
+ * Similar to the pattern used in other VSCode extensions
+ *
+ * @param relativePath - Relative path from extension root (e.g., 'assets/icon.png')
+ * @returns Full webview-accessible URL
+ *
+ * @example
+ * ```tsx
+ * <img src={generateResourceUrl('assets/icon.png')} />
+ * ```
+ */
+export function generateResourceUrl(relativePath: string): string {
+  const extensionUri = getExtensionUri();
+
+  if (!extensionUri) {
+    console.warn('[resourceUrl] Extension URI not found in window or body');
+    return '';
+  }
+
+  // Remove leading slash if present
+  const cleanPath = relativePath.startsWith('/')
+    ? relativePath.slice(1)
+    : relativePath;
+
+  // Ensure extension URI has trailing slash
+  const baseUri = extensionUri.endsWith('/')
+    ? extensionUri
+    : `${extensionUri}/`;
+
+  return `${baseUri}${cleanPath}`;
+}
+
+/**
+ * Shorthand for generating icon URLs
+ * @param iconPath - Path relative to assets directory
+ */
+export function generateIconUrl(iconPath: string): string {
+  return generateResourceUrl(`assets/${iconPath}`);
+}