style(ui): tweak compact ref and repo-tab-close sizing

Increase the compact reference overflow to 20px and slightly raise its
mono font to improve legibility and vertical alignment. Add explicit
square sizing and an aspect-ratio for the repo tab close control so
its icon and layout remain consistent across breakpoints and overrides.
Use !important on the size rules to ensure they take precedence.

- bump .compact-ref-overflow height and font-size for alignment
- add fixed sizing and aspect-ratio for repo tab close button

src/app.css

@@ -2960,15 +2960,15 @@
   .compact-ref-overflow {
     flex: 0 0 auto;
     min-width: 29px;
-    min-height: 19px;
+    min-height: 20px !important;
-    height: 19px;
+    height: 20px !important;
     padding: 0 5px;
     border-color: transparent;
     border-radius: 4px;
     color: var(--color-ink-dim);
     background: rgba(255,255,255,0.025);
     font-family: var(--font-mono);
-    font-size: 9px;
+    font-size: 9.5px;
     font-weight: 800;
   }
   .compact-ref-overflow:hover:not(:disabled),
@@ -6113,6 +6113,16 @@ input:focus, textarea:focus, select:focus { box-shadow: 0 0 0 3px color-mix(in s
 .repo-tab-wrap:first-child { border-left: 1px solid var(--color-border-subtle); }
 .repo-tab-wrap.active { background: var(--color-surface-solid); box-shadow: inset 0 -3px 0 var(--color-primary); }
 .repo-tab { min-height: 45px; padding-left: 14px; font-size: 12.5px; }
+.repo-tab-close {
+  width: 26px;
+  min-width: 26px;
+  max-width: 26px;
+  height: 26px;
+  min-height: 26px;
+  max-height: 26px;
+  flex-basis: 26px;
+  aspect-ratio: 1;
+}
 .repo-tab-add { min-height: 45px; }
 
 .repo-toolbar {