Implement duty schedule import functionality and enhance user management

- Added a new command `/import_duty_schedule` for importing duty schedules via JSON, restricted to admin users.
- Introduced a two-step import process: specifying handover time and uploading a JSON file.
- Updated the database schema to allow `telegram_user_id` to be nullable for user creation by full name.
- Implemented repository functions for user management, including `get_or_create_user_by_full_name` and `delete_duties_in_range`.
- Enhanced README documentation with details on the new import command and JSON format requirements.
- Added comprehensive tests for the duty schedule parser and integration tests for the import functionality.

tests/test_duty_schedule_parser.py

@@ -0,0 +1,92 @@
+"""Tests for duty-schedule JSON parser."""
+
+from datetime import date
+
+import pytest
+
+from importers.duty_schedule import (
+    DUTY_MARKERS,
+    DutyScheduleParseError,
+    parse_duty_schedule,
+)
+
+
+def test_parse_valid_schedule():
+    raw = (
+        '{"meta": {"start_date": "2026-02-16", "weeks": 2}, '
+        '"schedule": ['
+        '{"name": "Ivanov I.I.", "duty": "; ; \u0431 ; \u0411 ; \u0432 ; ;"}, '
+        '{"name": "Petrov P.P.", "duty": " ; \u041d ; \u041e ; ; ; ;"}'
+        "]}"
+    ).encode("utf-8")
+    result = parse_duty_schedule(raw)
+    assert result.start_date == date(2026, 2, 16)
+    # Petrov has 7 cells -> end = start + 6
+    assert result.end_date == date(2026, 2, 22)
+    assert len(result.entries) == 2
+    names = [e[0] for e in result.entries]
+    assert "Ivanov I.I." in names
+    assert "Petrov P.P." in names
+    by_name = {e[0]: e[1] for e in result.entries}
+    # Ivanov: indices 2, 3, 4 are duty (б, Б, в) -> 2026-02-18, 19, 20
+    ivan_dates = sorted(by_name["Ivanov I.I."])
+    assert ivan_dates == [date(2026, 2, 18), date(2026, 2, 19), date(2026, 2, 20)]
+    # Petrov: indices 1, 2 (Н, О) -> 2026-02-17, 18
+    petr_dates = sorted(by_name["Petrov P.P."])
+    assert petr_dates == [date(2026, 2, 17), date(2026, 2, 18)]
+
+
+def test_parse_empty_duty_string():
+    raw = b'{"meta": {"start_date": "2026-02-01"}, "schedule": [{"name": "A", "duty": ""}]}'
+    result = parse_duty_schedule(raw)
+    assert result.start_date == date(2026, 2, 1)
+    assert result.end_date == date(2026, 2, 1)
+    assert result.entries == [("A", [])]
+
+
+def test_parse_invalid_json():
+    with pytest.raises(DutyScheduleParseError, match="Invalid JSON"):
+        parse_duty_schedule(b"not json")
+
+
+def test_parse_missing_meta():
+    with pytest.raises(DutyScheduleParseError, match="meta"):
+        parse_duty_schedule(b'{"schedule": []}')
+
+
+def test_parse_missing_start_date():
+    with pytest.raises(DutyScheduleParseError, match="start_date"):
+        parse_duty_schedule(b'{"meta": {"weeks": 1}, "schedule": []}')
+
+
+def test_parse_invalid_start_date():
+    with pytest.raises(DutyScheduleParseError, match="start_date|Invalid"):
+        parse_duty_schedule(b'{"meta": {"start_date": "not-a-date"}, "schedule": []}')
+
+
+def test_parse_missing_schedule():
+    with pytest.raises(DutyScheduleParseError, match="schedule"):
+        parse_duty_schedule(b'{"meta": {"start_date": "2026-02-01"}}')
+
+
+def test_parse_schedule_not_array():
+    with pytest.raises(DutyScheduleParseError, match="schedule"):
+        parse_duty_schedule(b'{"meta": {"start_date": "2026-02-01"}, "schedule": {}}')
+
+
+def test_parse_schedule_item_missing_name():
+    with pytest.raises(DutyScheduleParseError, match="name"):
+        parse_duty_schedule(
+            b'{"meta": {"start_date": "2026-02-01"}, "schedule": [{"duty": ";"}]}'
+        )
+
+
+def test_parse_schedule_item_empty_name():
+    with pytest.raises(DutyScheduleParseError, match="empty"):
+        parse_duty_schedule(
+            b'{"meta": {"start_date": "2026-02-01"}, "schedule": [{"name": "  ", "duty": ""}]}'
+        )
+
+
+def test_duty_markers():
+    assert "б" in DUTY_MARKERS and "Б" in DUTY_MARKERS and "в" in DUTY_MARKERS