feat(user): report on another user's time entries

- Add user_id parameter to fetch_issues_with_spent_time().
- Support numeric ID, login, or full name resolution.
- Reject ambiguous names and unknown users with clear messages.
- Add CLI flags: --user-id, --user-login, --user-name.
- Only allow one user flag at a time.
- Add ResourceNotFoundError handling.
- Update README with usage examples.
- Add tests for user resolution and CLI flags.

Closes #40

tests/test_cli.py

@@ -265,3 +265,39 @@ def test_cli_no_time_passed_to_formatter(mock_fetch, tmp_path):
 
     _, kwargs = mock_get_formatter.call_args
     assert kwargs.get("no_time") is True
+
+
+@mock.patch.dict(os.environ, VALID_ENV, clear=True)
+@mock.patch("redmine_reporter.cli.fetch_issues_with_spent_time")
+def test_cli_passes_user_id_to_fetch(mock_fetch):
+    """CLI --user-id передаётся в fetch_issues_with_spent_time."""
+    mock_fetch.return_value = None
+    main(["--date", "2026-01-01--2026-01-31", "--user-id", "42"])
+    _, kwargs = mock_fetch.call_args
+    assert kwargs["user_id"] == "42"
+
+
+@mock.patch.dict(os.environ, VALID_ENV, clear=True)
+@mock.patch("redmine_reporter.cli.fetch_issues_with_spent_time")
+def test_cli_passes_user_login_to_fetch(mock_fetch):
+    """CLI --user-login передаётся в fetch_issues_with_spent_time."""
+    mock_fetch.return_value = None
+    main(["--date", "2026-01-01--2026-01-31", "--user-login", "ivanov"])
+    _, kwargs = mock_fetch.call_args
+    assert kwargs["user_id"] == "ivanov"
+
+
+@mock.patch.dict(os.environ, VALID_ENV, clear=True)
+def test_cli_rejects_multiple_user_flags():
+    """CLI не принимает одновременно несколько флагов пользователя."""
+    code = main(
+        [
+            "--date",
+            "2026-01-01--2026-01-31",
+            "--user-id",
+            "42",
+            "--user-login",
+            "ivanov",
+        ]
+    )
+    assert code == 1