feat(vscode-ide-companion): implement manual login via /login command

BREAKING CHANGE: Login is no longer automatic when opening webview

Changes:
- Remove auto-login on webview open and restore
- Add /login slash command for manual authentication
- Add VSCode progress notification during login process
- Add warning notification when user tries to chat without login
- Implement pending message auto-retry after successful login
- Add NotLoggedInMessage component (for future use)
- Improve InfoBanner close button styling consistency

User flow:
1. Open webview - no automatic login
2. Type /login or select from completion menu to login
3. Show "Logging in to Qwen Code..." progress notification
4. After login, show success message and auto-retry pending messages
5. If user tries to chat without login, show warning with "Login Now" button

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

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

packages/vscode-ide-companion/src/webview/components/NotLoggedInMessage.tsx

@@ -0,0 +1,126 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+import type React from 'react';
+
+interface NotLoggedInMessageProps {
+  /**
+   * The message to display
+   */
+  message: string;
+
+  /**
+   * Callback when the login button is clicked
+   */
+  onLoginClick: () => void;
+
+  /**
+   * Callback when the message is dismissed (optional)
+   */
+  onDismiss?: () => void;
+}
+
+export const NotLoggedInMessage: React.FC<NotLoggedInMessageProps> = ({
+  message,
+  onLoginClick,
+  onDismiss,
+}) => (
+    <div
+      className="flex items-start gap-3 p-4 my-4 rounded-lg"
+      style={{
+        backgroundColor: 'var(--app-warning-background)',
+        borderLeft: '3px solid var(--app-warning-border)',
+      }}
+    >
+      {/* Warning Icon */}
+      <svg
+        xmlns="http://www.w3.org/2000/svg"
+        viewBox="0 0 20 20"
+        fill="currentColor"
+        className="flex-shrink-0 w-5 h-5 mt-0.5"
+        style={{ color: 'var(--app-warning-foreground)' }}
+      >
+        <path
+          fillRule="evenodd"
+          d="M8.485 2.495c.673-1.167 2.357-1.167 3.03 0l6.28 10.875c.673 1.167-.17 2.625-1.516 2.625H3.72c-1.347 0-2.189-1.458-1.515-2.625L8.485 2.495ZM10 5a.75.75 0 0 1 .75.75v3.5a.75.75 0 0 1-1.5 0v-3.5A.75.75 0 0 1 10 5Zm0 9a1 1 0 1 0 0-2 1 1 0 0 0 0 2Z"
+          clipRule="evenodd"
+        />
+      </svg>
+
+      {/* Content */}
+      <div className="flex-1 min-w-0">
+        <p
+          className="m-0 mb-3 text-sm leading-relaxed"
+          style={{ color: 'var(--app-primary-foreground)' }}
+        >
+          {message}
+        </p>
+
+        {/* Login Button */}
+        <button
+          className="px-4 py-2 text-sm font-medium rounded transition-colors duration-200"
+          style={{
+            backgroundColor: 'var(--app-qwen-orange)',
+            color: 'white',
+            border: 'none',
+          }}
+          onMouseEnter={(e) => {
+            e.currentTarget.style.opacity = '0.9';
+          }}
+          onMouseLeave={(e) => {
+            e.currentTarget.style.opacity = '1';
+          }}
+          onClick={() => {
+            if (onDismiss) {
+              onDismiss();
+            }
+            onLoginClick();
+          }}
+        >
+          Login Now
+        </button>
+      </div>
+
+      {/* Optional Close Button */}
+      {onDismiss && (
+        <button
+          className="flex-shrink-0 flex items-center justify-center cursor-pointer rounded"
+          style={{
+            background: 'none',
+            border: 'none',
+            padding: '6px',
+            color: 'var(--app-secondary-foreground)',
+            borderRadius: '4px',
+          }}
+          onMouseEnter={(e) => {
+            e.currentTarget.style.backgroundColor =
+              'var(--app-ghost-button-hover-background)';
+          }}
+          onMouseLeave={(e) => {
+            e.currentTarget.style.backgroundColor = 'transparent';
+          }}
+          aria-label="Dismiss"
+          onClick={onDismiss}
+        >
+          <svg
+            className="w-[10px] h-[10px]"
+            width="10"
+            height="10"
+            viewBox="0 0 14 14"
+            fill="none"
+            xmlns="http://www.w3.org/2000/svg"
+          >
+            <path
+              d="M1 1L13 13M1 13L13 1"
+              stroke="currentColor"
+              strokeWidth="1.5"
+              strokeLinecap="round"
+            />
+          </svg>
+        </button>
+      )}
+    </div>
+  );