Add conversation and message model selection

internal/service/static/css/main.css

@@ -141,6 +141,7 @@ body {
 }
 
 .compose__action-btn {
+  flex-shrink: 0;
   display: flex;
   align-items: center;
   justify-content: center;
@@ -241,14 +242,32 @@ body {
   display: flex;
   align-items: center;
   gap: 0.125rem;
+  min-width: 0;
+  flex: 1;
 }
 
 .compose__actions-right {
+  flex-shrink: 0;
   display: flex;
   align-items: center;
   gap: 0.125rem;
 }
 
+.compose__model {
+  padding: 0 var(--s-1);
+  font-size: 0.7rem;
+  font-family: var(--font-mono);
+  color: var(--color-text-muted);
+  overflow: hidden;
+  text-overflow: ellipsis;
+  white-space: nowrap;
+  line-height: 1;
+}
+
+.compose__model:empty {
+  display: none;
+}
+
 .compose__attachment {
   display: flex;
   align-items: center;