Add search, filter, and sort to Admin Panel user management

Same UX improvements as the modal — search bar, group filter chips,
sortable column headers, and filtered count. Applied to the in-page
UserManagementPanel in AdminPage.js so the Admin Panel tab has
parity with the modal.

frontend/src/components/pages/AdminPage.js

@@ -117,6 +117,10 @@ function UserManagementPanel() {
   const [formError, setFormError] = useState('');
   const [successMessage, setSuccessMessage] = useState('');
   const [pendingConfirm, setPendingConfirm] = useState(null);
+  const [searchTerm, setSearchTerm] = useState('');
+  const [groupFilter, setGroupFilter] = useState('');
+  const [sortField, setSortField] = useState('username');
+  const [sortDir, setSortDir] = useState('asc');
 
   const fetchUsers = useCallback(async () => {
     setLoading(true);
@@ -148,6 +152,43 @@ function UserManagementPanel() {
     }
   }, [successMessage]);
 
+  // Filtered and sorted user list
+  const filteredUsers = users
+    .filter(u => {
+      if (searchTerm) {
+        const term = searchTerm.toLowerCase();
+        const matchesName = u.username?.toLowerCase().includes(term);
+        const matchesEmail = u.email?.toLowerCase().includes(term);
+        const matchesTeam = (u.teams || []).some(t => t.toLowerCase().includes(term));
+        if (!matchesName && !matchesEmail && !matchesTeam) return false;
+      }
+      if (groupFilter === 'no-teams') return !u.teams || u.teams.length === 0;
+      if (groupFilter && u.group !== groupFilter) return false;
+      return true;
+    })
+    .sort((a, b) => {
+      let aVal, bVal;
+      switch (sortField) {
+        case 'username': aVal = a.username || ''; bVal = b.username || ''; break;
+        case 'email': aVal = a.email || ''; bVal = b.email || ''; break;
+        case 'group': aVal = a.group || ''; bVal = b.group || ''; break;
+        case 'active': aVal = a.is_active ? 'a' : 'z'; bVal = b.is_active ? 'a' : 'z'; break;
+        case 'last_login': aVal = a.last_login || ''; bVal = b.last_login || ''; break;
+        default: aVal = a.username || ''; bVal = b.username || '';
+      }
+      const cmp = String(aVal).localeCompare(String(bVal));
+      return sortDir === 'asc' ? cmp : -cmp;
+    });
+
+  const handleSort = (field) => {
+    if (sortField === field) {
+      setSortDir(d => d === 'asc' ? 'desc' : 'asc');
+    } else {
+      setSortField(field);
+      setSortDir('asc');
+    }
+  };
+
   const handleAddClick = () => {
     setEditingUser(null);
     setFormData({ username: '', email: '', password: '', group: 'Read_Only' });
@@ -433,6 +474,48 @@ function UserManagementPanel() {
 
       {/* User table */}
       {!loading && !error && (
+        <div>
+          {/* Search and filter controls */}
+          <div style={{ display: 'flex', flexDirection: 'column', gap: '0.625rem', marginBottom: '0.75rem' }}>
+            <div style={{ position: 'relative' }}>
+              <Search style={{ position: 'absolute', left: '0.75rem', top: '50%', transform: 'translateY(-50%)', width: '14px', height: '14px', color: '#475569' }} />
+              <input
+                type="text"
+                placeholder="Search by name, email, or team..."
+                value={searchTerm}
+                onChange={e => setSearchTerm(e.target.value)}
+                style={{
+                  width: '100%', padding: '0.5rem 0.75rem 0.5rem 2.25rem',
+                  background: 'rgba(15, 23, 42, 0.6)',
+                  border: '1px solid rgba(14, 165, 233, 0.2)',
+                  borderRadius: '0.375rem', color: '#E2E8F0',
+                  fontSize: '0.8rem', fontFamily: 'monospace', outline: 'none',
+                }}
+              />
+            </div>
+            <div style={{ display: 'flex', gap: '0.3rem', flexWrap: 'wrap', alignItems: 'center' }}>
+              <span style={{ fontSize: '0.65rem', color: '#64748B', marginRight: '0.25rem' }}>Filter:</span>
+              {['', 'Admin', 'Standard_User', 'Leadership', 'Read_Only', 'no-teams'].map(g => (
+                <button
+                  key={g}
+                  onClick={() => setGroupFilter(g)}
+                  style={{
+                    padding: '0.15rem 0.5rem', borderRadius: '0.25rem',
+                    fontSize: '0.65rem', fontFamily: 'monospace', fontWeight: 600, cursor: 'pointer',
+                    border: groupFilter === g ? '1px solid #0EA5E9' : '1px solid rgba(14,165,233,0.2)',
+                    background: groupFilter === g ? 'rgba(14,165,233,0.15)' : 'transparent',
+                    color: groupFilter === g ? '#0EA5E9' : '#94A3B8',
+                  }}
+                >
+                  {g === '' ? 'All' : g === 'no-teams' ? 'No Teams' : g.replace('_', ' ')}
+                </button>
+              ))}
+              <span style={{ marginLeft: 'auto', fontSize: '0.65rem', color: '#64748B' }}>
+                {filteredUsers.length} of {users.length} users
+              </span>
+            </div>
+          </div>
+
         <div style={{
           background: 'linear-gradient(135deg, rgba(30,41,59,0.95) 0%, rgba(15,23,42,0.98) 100%)',
           border: '1px solid rgba(14,165,233,0.15)',
@@ -448,21 +531,21 @@ function UserManagementPanel() {
             fontSize: '0.62rem', color: '#334155',
             fontFamily: 'monospace', textTransform: 'uppercase', letterSpacing: '0.08em',
           }}>
-            <span>Username</span>
-            <span>Email</span>
-            <span>Group</span>
-            <span>Active</span>
-            <span>Last Login</span>
+            <span style={{ cursor: 'pointer' }} onClick={() => handleSort('username')}>Username {sortField === 'username' ? (sortDir === 'asc' ? '▲' : '▼') : ''}</span>
+            <span style={{ cursor: 'pointer' }} onClick={() => handleSort('email')}>Email {sortField === 'email' ? (sortDir === 'asc' ? '▲' : '▼') : ''}</span>
+            <span style={{ cursor: 'pointer' }} onClick={() => handleSort('group')}>Group {sortField === 'group' ? (sortDir === 'asc' ? '▲' : '▼') : ''}</span>
+            <span style={{ cursor: 'pointer' }} onClick={() => handleSort('active')}>Active {sortField === 'active' ? (sortDir === 'asc' ? '▲' : '▼') : ''}</span>
+            <span style={{ cursor: 'pointer' }} onClick={() => handleSort('last_login')}>Last Login {sortField === 'last_login' ? (sortDir === 'asc' ? '▲' : '▼') : ''}</span>
             <span style={{ textAlign: 'right' }}>Actions</span>
           </div>
 
           {/* Rows */}
-          {users.length === 0 ? (
+          {filteredUsers.length === 0 ? (
             <div style={{ padding: '2rem', textAlign: 'center', color: '#334155', fontFamily: 'monospace', fontSize: '0.8rem' }}>
               No users found
             </div>
           ) : (
-            users.map(u => {
+            filteredUsers.map(u => {
               const badge = getGroupBadgeStyle(u.group);
               const self = isSelfUser(currentUser?.id, u.id);
               return (
@@ -575,6 +658,7 @@ function UserManagementPanel() {
             })
           )}
         </div>
+        </div>
       )}
 
       {/* Confirmation Modal */}