Implement the birthday wisher core (MIL-002)

Layered package (domain, application, infrastructure, presentation), CLI with
--dry-run and --today, SMTP with STARTTLS behind a port, 56 offline tests and
the Python code review RC-006.

Task: MIL-002#1
Task: MIL-002#2
Task: MIL-002#3
Task: MIL-002#4
Task: MIL-002#5
Task: MIL-002#6
Refs #7
Refs #8
Refs #9
Refs #10
Refs #11
Refs #12

tests/integration/infrastructure/test_csv_birthday_repository.py

@@ -0,0 +1,63 @@
+"""Integration tests for CsvBirthdayRepository against real files."""
+
+from pathlib import Path
+
+import pytest
+
+from birthday_wisher.domain.errors import BirthdayDataError
+from birthday_wisher.domain.person import Person
+from birthday_wisher.infrastructure.csv_birthday_repository import (
+    CsvBirthdayRepository,
+)
+
+HEADER = "name,email,year,month,day\n"
+
+
+def _write(tmp_path: Path, text: str) -> Path:
+    path = tmp_path / "birthdays.csv"
+    path.write_text(text, encoding="utf-8")
+    return path
+
+
+def test_load_all_reads_people_in_file_order(tmp_path: Path) -> None:
+    """Rows become Person objects in file order."""
+    path = _write(
+        tmp_path,
+        HEADER + "Ann,ann@example.com,1990,3,14\nBob,bob@example.com,1985,10,17\n",
+    )
+    assert CsvBirthdayRepository(path).load_all() == [
+        Person("Ann", "ann@example.com", 1990, 3, 14),
+        Person("Bob", "bob@example.com", 1985, 10, 17),
+    ]
+
+
+def test_load_all_header_only_gives_empty_list(tmp_path: Path) -> None:
+    """A file with only a header holds nobody."""
+    assert CsvBirthdayRepository(_write(tmp_path, HEADER)).load_all() == []
+
+
+def test_load_all_missing_file_raises(tmp_path: Path) -> None:
+    """A missing file raises BirthdayDataError."""
+    with pytest.raises(BirthdayDataError):
+        CsvBirthdayRepository(tmp_path / "nope.csv").load_all()
+
+
+def test_load_all_missing_column_raises(tmp_path: Path) -> None:
+    """A missing column is named in the error."""
+    path = _write(tmp_path, "name,email,year,month\nAnn,a@example.com,1990,3\n")
+    with pytest.raises(BirthdayDataError, match="day"):
+        CsvBirthdayRepository(path).load_all()
+
+
+def test_load_all_non_numeric_value_raises(tmp_path: Path) -> None:
+    """A non-numeric month raises and names the line."""
+    path = _write(tmp_path, HEADER + "Ann,a@example.com,1990,March,14\n")
+    with pytest.raises(BirthdayDataError, match="line 2"):
+        CsvBirthdayRepository(path).load_all()
+
+
+def test_load_all_short_row_raises(tmp_path: Path) -> None:
+    """A row with too few fields raises BirthdayDataError."""
+    path = _write(tmp_path, HEADER + "Ann,a@example.com,1990\n")
+    with pytest.raises(BirthdayDataError):
+        CsvBirthdayRepository(path).load_all()