style(fe): standardize filter inputs in ApprovalQueue page

- Input height: 34px (standard KBX compact)
- Padding: 0 0.75rem
- Line-height: 34px for vertical centering
- Box-sizing: border-box for consistent sizing
- Change filters from grid to flex layout
- Remove margin-bottom (handled by PageLayout)
- Filter gap: var(--ks-space-3) (matches other pages)

Aligns with PageLayout + ModelsList + ShadowRunQueue standardization.

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

frontend/src/features/approval/pages/ApprovalQueue.vue

@@ -380,20 +380,21 @@ h3 {
 }
 
 .filters {
-  display: grid;
-  grid-template-columns: repeat(2, 1fr);
-  gap: var(--spacing-4);
-  margin-bottom: var(--spacing-5);
+  display: flex;
+  gap: var(--ks-space-3);
 }
 
 .input {
-  padding: var(--spacing-2) var(--spacing-3);
+  height: 34px;
+  padding: 0 0.75rem;
   border: var(--border-width-1) solid var(--color-input-border);
-  border-radius: var(--border-radius-base);
+  border-radius: 4px;
   background: var(--color-input-background);
   color: var(--color-text-primary);
-  font-size: var(--font-size-sm);
+  font-size: 13px;
   font-family: var(--font-sans);
+  line-height: 34px;
+  box-sizing: border-box;
   transition: all var(--transition-fast);
 }