Refactor AI chat: streaming, tool calls, UI polish

apps/admin/src/components/AiChat/style.css

@@ -9,6 +9,7 @@
 }
 
 .ai-chat-layout {
+  position: relative;
   display: flex;
   height: 100%;
   min-height: 0;
@@ -38,6 +39,10 @@
   overflow-y: auto;
 }
 
+.ai-chat-sidebar .ant-conversations-creation {
+  margin-bottom: 8px;
+}
+
 .ai-chat-sidebar__loading {
   position: absolute;
   inset: 68px 0 auto;
@@ -62,10 +67,22 @@
 }
 
 .ai-chat-toolbar .ant-typography {
+  flex: 1 1 auto;
   min-width: 0;
   font-weight: 600;
 }
 
+.ai-chat-welcome {
+  display: grid;
+  width: min(720px, 100%);
+  gap: 20px;
+  padding: 32px;
+}
+
+.ai-chat-welcome .ant-welcome-icon {
+  color: #007aff;
+}
+
 .ai-chat-messages {
   display: flex;
   flex: 1 1 auto;
@@ -91,6 +108,10 @@
   white-space: pre-wrap;
 }
 
+.ai-chat-user-content {
+  max-width: 100%;
+}
+
 .ai-chat-answer {
   width: 100%;
   min-width: 0;
@@ -108,33 +129,11 @@
   overflow-x: auto;
 }
 
-.ai-chat-tools {
-  display: grid;
-  gap: 6px;
-  padding: 8px 10px;
-  background: #f7f7f8;
-  border: 1px solid #ededf0;
-  border-radius: 8px;
-}
-
-.ai-chat-tool {
-  display: flex;
-  align-items: flex-start;
-  gap: 6px;
-  min-width: 0;
-}
-
-.ai-chat-tool .ant-tag {
-  flex: 0 0 auto;
-  margin: 0;
-}
-
-.ai-chat-tool__summary {
-  min-width: 0;
-  overflow: hidden;
-  font-size: 12px;
-  text-overflow: ellipsis;
-  white-space: nowrap;
+.ai-chat-answer .ant-thought-chain {
+  padding: 10px 12px;
+  background: #f7f8fa;
+  border: 1px solid #eceef2;
+  border-radius: 10px;
 }
 
 .ai-chat-composer {
@@ -144,6 +143,15 @@
   border-top: 1px solid #ededf0;
 }
 
+.ai-chat-composer .ant-sender {
+  max-width: 820px;
+  margin: 0 auto;
+}
+
+.ai-chat-composer .ant-attachments {
+  max-width: 820px;
+}
+
 .ai-chat-composer .ant-sender-input:focus,
 .ai-chat-composer .ant-sender-input:focus-visible,
 .ai-chat-composer .ant-sender-input:focus-within {