feat: add search_users and count_users to user repository

tests/test_store/test_sqlite_user_repo.py

@@ -159,6 +159,49 @@ async def test_create_duplicate_username(user_repo: SQLiteUserRepository) -> Non
         await user_repo.create(_make_user(userid="different-id", username="alice"))
 
 
+async def test_search_users_by_username(user_repo: SQLiteUserRepository) -> None:
+    await user_repo.create(_make_user(userid="id-1", username="sample_user"))
+    results = await user_repo.search_users("sample", offset=0, limit=100)
+    assert len(results) == 1
+    assert results[0].userid == "id-1"
+
+
+async def test_search_users_by_email(user_repo: SQLiteUserRepository) -> None:
+    await user_repo.create(_make_user(email="alice@example.com"))
+    results = await user_repo.search_users("alice", offset=0, limit=100)
+    assert len(results) == 1
+
+
+async def test_search_users_no_match(user_repo: SQLiteUserRepository) -> None:
+    await user_repo.create(_make_user())
+    results = await user_repo.search_users("nonexistent", offset=0, limit=100)
+    assert len(results) == 0
+
+
+async def test_search_users_pagination(user_repo: SQLiteUserRepository) -> None:
+    for i in range(5):
+        await user_repo.create(_make_user(userid=f"id-{i}", username=f"user{i}", groups=["users"]))
+    page1 = await user_repo.search_users("user", offset=0, limit=2)
+    page2 = await user_repo.search_users("user", offset=2, limit=2)
+    assert len(page1) == 2
+    assert len(page2) == 2
+    assert page1[0].username != page2[0].username
+
+
+async def test_count_users_no_query(user_repo: SQLiteUserRepository) -> None:
+    await user_repo.create(_make_user())
+    count = await user_repo.count_users()
+    assert count == 1
+
+
+async def test_count_users_with_query(user_repo: SQLiteUserRepository) -> None:
+    await user_repo.create(_make_user())
+    count = await user_repo.count_users(query="alice")
+    assert count == 1
+    count = await user_repo.count_users(query="nonexistent")
+    assert count == 0
+
+
 async def test_roundtrip_preserves_all_fields(user_repo: SQLiteUserRepository) -> None:
     user = _make_user(
         preferred_username="ally",