refactor(vscode-ide-companion): extract AssistantMessage as standalone component with Claude Code styles

- Extract AssistantMessage component from inline implementation
- Add status prop support (default, success, error, warning, loading)
- Implement bullet point indicator using CSS pseudo-elements (::before)
- Use inline styles for layout to prevent Tailwind override
- Add AssistantMessage.css with pseudo-element styles for different states
- Import AssistantMessage.css in ClaudeCodeStyles.css

Restores Claude Code DOM structure and styling:
- Outer container with padding-left: 30px for bullet spacing
- Bullet point colors based on status (green, red, yellow, gray)
- Loading state with pulse animation

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

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

packages/vscode-ide-companion/src/webview/components/messages/AssistantMessage.css

@@ -0,0 +1,60 @@
+/**
+ * @license
+ * Copyright 2025 Qwen Team
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * AssistantMessage Component Styles
+ * Only pseudo-elements (::before) for bullet points
+ */
+
+/* Bullet point indicator using ::before pseudo-element */
+.assistant-message-container.assistant-message-default::before,
+.assistant-message-container.assistant-message-success::before,
+.assistant-message-container.assistant-message-error::before,
+.assistant-message-container.assistant-message-warning::before,
+.assistant-message-container.assistant-message-loading::before {
+  content: '\25cf';
+  position: absolute;
+  left: 8px;
+  padding-top: 2px;
+  font-size: 10px;
+  z-index: 1;
+}
+
+/* Default state - secondary foreground color */
+.assistant-message-container.assistant-message-default::before {
+  color: var(--app-secondary-foreground);
+}
+
+/* Success state - green bullet (maps to .ge) */
+.assistant-message-container.assistant-message-success::before {
+  color: #74c991;
+}
+
+/* Error state - red bullet (maps to .be) */
+.assistant-message-container.assistant-message-error::before {
+  color: #c74e39;
+}
+
+/* Warning state - yellow/orange bullet (maps to .ue) */
+.assistant-message-container.assistant-message-warning::before {
+  color: #e1c08d;
+}
+
+/* Loading state - animated bullet (maps to .he) */
+.assistant-message-container.assistant-message-loading::before {
+  color: var(--app-secondary-foreground);
+  background-color: var(--app-secondary-background);
+  animation: assistantMessagePulse 1s linear infinite;
+}
+
+/* Pulse animation for loading state */
+@keyframes assistantMessagePulse {
+  0%,
+  100% {
+    opacity: 1;
+  }
+  50% {
+    opacity: 0.5;
+  }
+}