refactor(fe): implement responsive flex-based layout for ModelsList

- Grid height: height: 100% (leverages PageLayout flex)
- Filter inputs: Standard 34px height (KBX compact)
- Removes hardcoded calc() and max/min constraints
- Automatically adjusts to viewport/container changes
- No manual adjustments needed per screen size

This allows the component to scale responsively within
the PageLayout flex container without additional CSS.

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>

frontend/src/features/models/pages/ModelsList.vue

@@ -191,15 +191,15 @@ function handleSearch() {
 
 .search-input,
 .status-select {
-  height: var(--kbx-input-height, 34px);
+  height: 34px;
-  padding: var(--kbx-input-padding-y, 0.5rem) var(--kbx-input-padding-x, 0.75rem);
+  padding: 0 0.75rem;
   border: 1px solid var(--color-border-primary);
-  border-radius: var(--kbx-border-radius-sm, 4px);
+  border-radius: 4px;
   background-color: var(--color-background-primary);
   color: var(--color-text-primary);
-  font-size: var(--kbx-font-size-input, 0.875rem);
+  font-size: 13px;
-  font-family: var(--kbx-font-family-base, inherit);
+  font-family: inherit;
-  line-height: 1.4;
+  line-height: 34px;
   box-sizing: border-box;
 }
 
@@ -228,8 +228,7 @@ function handleSearch() {
   border: 1px solid var(--color-border-primary);
   border-radius: var(--kbx-border-radius-sm, 4px);
   overflow: hidden;
-  height: calc(100vh - 400px);
+  height: 100%;
-  max-height: 600px;
   min-height: 300px;
   display: flex;
   flex-direction: column;