Initial commit: event-driven UK payslip ingest service

Extracted from /home/wizard/code monorepo into its own repo so Woodpecker CI
can watch it. Identical content to /home/wizard/code commit e426028.

See README.md for overview, env vars, and Paperless workflow config.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

tests/test_schema.py

@@ -0,0 +1,52 @@
+from decimal import Decimal
+
+import pytest
+from pydantic import ValidationError
+
+from payslip_ingest.schema import ExtractedPayslip, validate_totals
+
+
+def _sample_payload() -> dict[str, object]:
+    return {
+        "pay_date": "2026-03-28",
+        "pay_period_start": "2026-03-01",
+        "pay_period_end": "2026-03-31",
+        "employer": "Acme Ltd",
+        "currency": "GBP",
+        "gross_pay": "5000.00",
+        "income_tax": "800.00",
+        "national_insurance": "350.00",
+        "pension_employee": "250.00",
+        "pension_employer": "150.00",
+        "student_loan": "100.00",
+        "other_deductions": {
+            "cycle_to_work": "50.00"
+        },
+        "net_pay": "3450.00",
+    }
+
+
+def test_schema_accepts_realistic_payload() -> None:
+    model = ExtractedPayslip.model_validate(_sample_payload())
+    assert model.employer == "Acme Ltd"
+    assert model.gross_pay == Decimal("5000.00")
+    assert model.other_deductions == {"cycle_to_work": Decimal("50.00")}
+
+
+def test_schema_rejects_extra_fields() -> None:
+    payload = _sample_payload()
+    payload["bonus_field"] = "not allowed"
+    with pytest.raises(ValidationError):
+        ExtractedPayslip.model_validate(payload)
+
+
+def test_validate_totals_true_for_matched_numbers() -> None:
+    model = ExtractedPayslip.model_validate(_sample_payload())
+    assert validate_totals(model) is True
+
+
+def test_validate_totals_false_for_mismatch() -> None:
+    payload = _sample_payload()
+    payload["net_pay"] = "4000.00"
+    model = ExtractedPayslip.model_validate(payload)
+    assert validate_totals(model) is False