feat: enhance error handling and configuration validation

- Added a global exception handler to log unhandled exceptions and return a generic 500 JSON response without exposing details to the client.
- Updated the configuration to validate the `DATABASE_URL` format, ensuring it starts with `sqlite://` or `postgresql://`, and log warnings for invalid formats.
- Introduced safe parsing for numeric environment variables (`HTTP_PORT`, `INIT_DATA_MAX_AGE_SECONDS`) with defaults on invalid values, including logging warnings for out-of-range values.
- Enhanced the duty schedule parser to enforce limits on the number of schedule rows and the length of full names and duty strings, raising appropriate errors when exceeded.
- Updated internationalization messages to include generic error responses for import failures and parsing issues, improving user experience.
- Added unit tests to verify the new error handling and configuration validation behaviors.

tests/test_duty_schedule_parser.py

@@ -1,11 +1,14 @@
 """Tests for duty-schedule JSON parser."""
 
+import json
 from datetime import date
 
 import pytest
 
 from duty_teller.importers.duty_schedule import (
     DUTY_MARKERS,
+    MAX_FULL_NAME_LENGTH,
+    MAX_SCHEDULE_ROWS,
     UNAVAILABLE_MARKER,
     VACATION_MARKER,
     DutyScheduleParseError,
@@ -118,3 +121,38 @@ def test_unavailable_and_vacation_markers():
     assert entry.unavailable_dates == [date(2026, 2, 1)]
     assert entry.vacation_dates == [date(2026, 2, 2)]
     assert entry.duty_dates == [date(2026, 2, 3)]
+
+
+def test_parse_start_date_year_out_of_range():
+    """start_date year must be current ± 1; otherwise DutyScheduleParseError."""
+    # Use a year far in the past/future so it fails regardless of test run date.
+    raw_future = b'{"meta": {"start_date": "2030-01-01"}, "schedule": [{"name": "A", "duty": ""}]}'
+    with pytest.raises(DutyScheduleParseError, match="year|2030"):
+        parse_duty_schedule(raw_future)
+    raw_past = b'{"meta": {"start_date": "2019-01-01"}, "schedule": [{"name": "A", "duty": ""}]}'
+    with pytest.raises(DutyScheduleParseError, match="year|2019"):
+        parse_duty_schedule(raw_past)
+
+
+def test_parse_too_many_schedule_rows():
+    """More than MAX_SCHEDULE_ROWS rows raises DutyScheduleParseError."""
+    rows = [{"name": f"User {i}", "duty": ""} for i in range(MAX_SCHEDULE_ROWS + 1)]
+    today = date.today()
+    start = today.replace(month=1, day=1)
+    payload = {"meta": {"start_date": start.isoformat()}, "schedule": rows}
+    raw = json.dumps(payload).encode("utf-8")
+    with pytest.raises(DutyScheduleParseError, match="too many|max"):
+        parse_duty_schedule(raw)
+
+
+def test_parse_full_name_too_long():
+    """full_name longer than MAX_FULL_NAME_LENGTH raises DutyScheduleParseError."""
+    long_name = "A" * (MAX_FULL_NAME_LENGTH + 1)
+    today = date.today()
+    start = today.replace(month=1, day=1)
+    raw = (
+        f'{{"meta": {{"start_date": "{start.isoformat()}"}}, '
+        f'"schedule": [{{"name": "{long_name}", "duty": ""}}]}}'
+    ).encode("utf-8")
+    with pytest.raises(DutyScheduleParseError, match="exceed|character"):
+        parse_duty_schedule(raw)