Add encodeURIComponent for username in API URL paths

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/stores/acctMgmt.test.js

@@ -114,6 +114,16 @@ describe('acctMgmtStore', () => {
       expect(result).toBe(true);
     });
 
+    it('encodes special characters in username', async () => {
+      mockDelete.mockResolvedValue({ status: 200 });
+
+      await store.deleteAccount('user@domain/name');
+
+      expect(mockDelete).toHaveBeenCalledWith(
+        '/api/users/user%40domain%2Fname',
+      );
+    });
+
     it('returns false on error', async () => {
       mockDelete.mockRejectedValue(new Error('fail'));
 
@@ -154,6 +164,16 @@ describe('acctMgmtStore', () => {
       );
       expect(result).toBe(true);
     });
+
+    it('encodes special characters in username and role', async () => {
+      mockPut.mockResolvedValue({ status: 200 });
+
+      await store.addRoleToUser('user@org', 'role/special');
+
+      expect(mockPut).toHaveBeenCalledWith(
+        '/api/users/user%40org/roles/role%2Fspecial',
+      );
+    });
   });
 
   describe('deleteRoleToUser', () => {