fix(web-ui): increase Prompts editor height for comfortable editing

- Raise min-height from 60vh to 75vh, remove max-height cap
- Mobile: 60vh min with no max-height limit
- Modal editor unchanged (space-constrained, fixed ratio appropriate)

Author: ymkiux

web-ui/styles/modals-core.css

@@ -501,6 +501,26 @@
 
 .prompts-editor {
     margin-top: 12px;
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+    min-height: 0;
+}
+
+.prompts-editor .form-group {
+    flex: 1;
+    display: flex;
+    flex-direction: column;
+    min-height: 0;
+}
+
+.prompts-editor .editor-frame {
+    min-height: 75vh;
+}
+
+.prompts-editor .template-editor {
+    min-height: 75vh;
+    max-height: none;
 }
 
 .prompts-editor-toolbar {

web-ui/styles/responsive.css

@@ -205,6 +205,11 @@ textarea:focus-visible {
         max-height: min(56vh, 480px);
     }
 
+    .prompts-editor .template-editor {
+        min-height: 60vh;
+        max-height: none;
+    }
+
     .status-strip {
         gap: 12px;
     }