style(ui): consolidate @layer base blocks per Greptile review

Move font-family: inherit declarations into the existing @layer base
block at line 117 instead of a separate block, keeping all base-layer
overrides in one place.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/index.css

@@ -142,6 +142,11 @@
   label {
     touch-action: manipulation;
   }
+  /* Let font-mono (utilities layer) override for monospace editors */
+  .paperclip-mdxeditor [class*="_placeholder_"],
+  .paperclip-mdxeditor-content {
+    font-family: inherit;
+  }
 }
 
 @media (pointer: coarse) {
@@ -319,13 +324,6 @@
   color: inherit;
 }
 
-@layer base {
-  .paperclip-mdxeditor [class*="_placeholder_"],
-  .paperclip-mdxeditor-content {
-    font-family: inherit;
-  }
-}
-
 .paperclip-edit-in-place-content {
   font-size: 0.9375rem;
   line-height: 1.75rem;