Refactor AI config to step-based wizard with DeepSeek defaults

apps/admin/src/pages/AiConfig/index.module.css

@@ -1,11 +1,11 @@
 .container {
-  max-width: 1200px;
+  max-width: 900px;
   margin: 0 auto;
   padding: 16px;
 }
 
 .header {
-  margin-bottom: 16px;
+  margin-bottom: 20px;
 }
 
 .header h2 {
@@ -24,17 +24,13 @@
   margin-top: 8px;
 }
 
-.grid {
-  display: grid;
-  grid-template-columns: 1fr 1fr;
-  gap: 16px;
-  margin-bottom: 16px;
+.steps {
+  margin-bottom: 24px;
 }
 
-@media (max-width: 768px) {
-  .grid {
-    grid-template-columns: 1fr;
-  }
+.stepContent {
+  min-height: 320px;
+  margin-bottom: 16px;
 }
 
 .cardTitle {
@@ -42,10 +38,17 @@
   font-weight: 600;
 }
 
-.actions {
+.stepNav {
   display: flex;
-  gap: 8px;
-  flex-wrap: wrap;
+  justify-content: space-between;
+  padding-top: 8px;
+  border-top: 1px solid #f0f0f0;
+}
+
+.modelFetchRow {
+  display: flex;
+  align-items: center;
+  gap: 12px;
 }
 
 .testResult {