fix(ui): Select dropdown caps menu height + shows empty-value option label

The kit Select now passes displayEmpty:true (so a selected value="" option like an "All" filter renders its label instead of a blank control) and MenuProps.PaperProps maxHeight:320 (so long option lists scroll inside the popover instead of listing every record). Both apply via slotProps.select and are overridable per call site. Verified app-wide: no call site regresses (audit of all 74 usages).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/admin/ui/Select.tsx

@@ -18,6 +18,7 @@ export default function Select({
   onChange,
   options,
   children,
+  slotProps,
   ...props
 }: SelectProps) {
   return (
@@ -29,6 +30,20 @@ export default function Select({
       value={value}
       onChange={(e) => onChange(e.target.value)}
       {...props}
+      slotProps={{
+        ...slotProps,
+        select: {
+          // Render the selected option's label even when its value is "" — e.g.
+          // an "All" filter option. Without displayEmpty MUI shows the control
+          // blank for an empty-string value despite it being selected.
+          displayEmpty: true,
+          // Cap the menu height so long option lists scroll inside the popover
+          // instead of growing to fit every record (and running off-screen).
+          MenuProps: { PaperProps: { sx: { maxHeight: 320 } } },
+          // Let callers override either default (e.g. a custom renderValue).
+          ...((slotProps as { select?: object } | undefined)?.select ?? {}),
+        },
+      }}
     >
       {options
         ? options.map((o) => (