refactor: use SplitPane and EntityList in Admin RBAC tabs

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/pages/Admin/UserManagement/UserManagement.module.css

@@ -1,63 +1,3 @@
-.splitPane {
-  display: grid;
-  grid-template-columns: 52fr 48fr;
-  gap: 1px;
-  background: var(--border-subtle);
-  border: 1px solid var(--border-subtle);
-  border-radius: var(--radius-lg);
-  min-height: 500px;
-  box-shadow: var(--shadow-card);
-}
-
-.listPane {
-  background: var(--bg-surface);
-  display: flex;
-  flex-direction: column;
-  border-radius: var(--radius-lg) 0 0 var(--radius-lg);
-}
-
-.detailPane {
-  background: var(--bg-surface);
-  overflow-y: auto;
-  padding: 20px;
-  border-radius: 0 var(--radius-lg) var(--radius-lg) 0;
-}
-
-.listHeader {
-  display: flex;
-  align-items: center;
-  gap: 8px;
-  padding: 12px;
-  border-bottom: 1px solid var(--border-subtle);
-}
-
-.listHeaderSearch {
-  flex: 1;
-}
-
-.entityList {
-  flex: 1;
-  overflow-y: auto;
-}
-
-.entityItem {
-  display: flex;
-  align-items: flex-start;
-  gap: 10px;
-  padding: 10px 12px;
-  cursor: pointer;
-  transition: background 0.1s;
-  border-bottom: 1px solid var(--border-subtle);
-}
-
-.entityItem:hover {
-  background: var(--bg-hover);
-}
-
-.entityItemSelected {
-  background: var(--bg-raised);
-}
-
 .entityInfo {
   flex: 1;
   min-width: 0;
@@ -140,16 +80,6 @@
   max-width: 240px;
 }
 
-.emptyDetail {
-  display: flex;
-  align-items: center;
-  justify-content: center;
-  height: 100%;
-  color: var(--text-faint);
-  font-size: 13px;
-  font-family: var(--font-body);
-}
-
 .createForm {
   padding: 12px;
   border-bottom: 1px solid var(--border-subtle);
@@ -190,14 +120,6 @@
   margin-top: 16px;
 }
 
-.emptySearch {
-  padding: 32px;
-  text-align: center;
-  color: var(--text-faint);
-  font-size: 12px;
-  font-family: var(--font-body);
-}
-
 .securitySection {
   margin-top: 8px;
   margin-bottom: 8px;