feat: add runtime proxy configuration support to browser_configure

Enables on-the-fly proxy switching without restarting MCP server, allowing
users to dynamically set or clear proxy settings during browser sessions.

Changes:
- Add proxyServer and proxyBypass parameters to updateBrowserConfig method
- Implement proxy set/clear logic with proper validation for empty strings
- Expose proxy configuration through browser_configure tool interface
- Update auto-generated documentation with proxy parameter descriptions

Tested with SOCKS5 proxy, verified IP changes when proxy is enabled/disabled.

src/context.ts

@@ -501,6 +501,10 @@ export class Context {
     permissions?: string[];
     offline?: boolean;
 
+    // Proxy Configuration
+    proxyServer?: string;
+    proxyBypass?: string;
+
     // Browser UI Customization
     chromiumSandbox?: boolean;
     slowMo?: number;
@@ -564,6 +568,21 @@ export class Context {
     if (changes.offline !== undefined)
       (currentConfig.browser as any).offline = changes.offline;
 
+    // Apply proxy configuration
+    if (changes.proxyServer !== undefined) {
+      if (changes.proxyServer === '' || changes.proxyServer === null) {
+        // Clear proxy when empty string or null
+        delete currentConfig.browser.launchOptions.proxy;
+      } else {
+        // Set proxy server
+        currentConfig.browser.launchOptions.proxy = {
+          server: changes.proxyServer
+        };
+        if (changes.proxyBypass)
+          currentConfig.browser.launchOptions.proxy.bypass = changes.proxyBypass;
+      }
+    }
+
     // Apply browser launch options for UI customization
     if (changes.chromiumSandbox !== undefined)
       currentConfig.browser.launchOptions.chromiumSandbox = changes.chromiumSandbox;