feat(admin): Add activity logs page and fix AI chat markdown rendering

- Add paginated activity logs API with filters (date, module, action, keyword)

- Add ActivityLogsPage with table, filters, and detail modal

- Add markdown rendering support for AI chat messages

- Remove prototype placeholder content from chat sidebar

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-v2/src/modules/aia/styles/chat-workspace.css

@@ -946,3 +946,93 @@
   border-radius: 8px;
 }
 
+/* ============================================ */
+/* MarkdownContent 组件样式 */
+/* ============================================ */
+.message-bubble .markdown-content {
+  white-space: normal;
+}
+
+.message-bubble .markdown-content p {
+  margin: 0 0 8px 0;
+}
+
+.message-bubble .markdown-content p:last-child {
+  margin-bottom: 0;
+}
+
+.message-bubble .markdown-content .md-divider {
+  border: none;
+  border-top: 1px solid #E5E7EB;
+  margin: 12px 0;
+}
+
+.message-bubble .markdown-content h1,
+.message-bubble .markdown-content h2,
+.message-bubble .markdown-content h3 {
+  margin: 16px 0 8px 0;
+  font-weight: 700;
+  line-height: 1.4;
+}
+
+.message-bubble .markdown-content h1:first-child,
+.message-bubble .markdown-content h2:first-child,
+.message-bubble .markdown-content h3:first-child {
+  margin-top: 0;
+}
+
+.message-bubble .markdown-content h1 {
+  font-size: 1.3em;
+}
+
+.message-bubble .markdown-content h2 {
+  font-size: 1.2em;
+}
+
+.message-bubble .markdown-content h3 {
+  font-size: 1.1em;
+}
+
+.message-bubble .markdown-content ul,
+.message-bubble .markdown-content ol {
+  margin: 8px 0 12px 0;
+  padding-left: 24px;
+}
+
+.message-bubble .markdown-content ul {
+  list-style-type: disc;
+}
+
+.message-bubble .markdown-content ol {
+  list-style-type: decimal;
+}
+
+.message-bubble .markdown-content li {
+  margin: 6px 0;
+  line-height: 1.6;
+  display: list-item;
+}
+
+.message-bubble .markdown-content li::marker {
+  color: #4F6EF2;
+}
+
+.message-bubble .markdown-content strong {
+  font-weight: 700;
+  color: #1F2937;
+}
+
+.message-bubble .markdown-content em {
+  font-style: italic;
+  color: #4B5563;
+}
+
+.message-bubble .markdown-content code {
+  background: rgba(79, 110, 242, 0.1);
+  color: #4F6EF2;
+  padding: 2px 6px;
+  border-radius: 4px;
+  font-family: 'Monaco', 'Consolas', 'Courier New', monospace;
+  font-size: 0.9em;
+}
+