Merge ie-email-parser: HTML + CSV fallbacks + failure-mode tests

# Conflicts:
#	broker_sync/providers/parsers/invest_engine.py
#	tests/providers/parsers/test_invest_engine.py

tests/providers/parsers/test_invest_engine.py

@@ -42,3 +42,67 @@ def test_rfc2822_notes_record_parse_strategy() -> None:
     a = parse_invest_engine_email(_load("rfc2822_v2_single_buy.eml"))[0]
     assert a.notes is not None
     assert "rfc2822" in a.notes
+
+
+# -- HTML table body (multipart/alternative, two orders) --
+
+
+def test_html_body_parses_both_orders() -> None:
+    activities = parse_invest_engine_email(_load("html_two_orders.eml"))
+    assert len(activities) == 2
+    a, b = activities
+    assert a.symbol == "VUAG"
+    assert a.quantity == Decimal("10.5")
+    assert a.unit_price == Decimal("62.10")
+    assert a.date == datetime(2026, 4, 1)
+    assert a.account_id == "invest-engine-primary"
+    assert a.account_type is AccountType.ISA
+    assert a.activity_type is ActivityType.BUY
+    assert b.symbol == "SWDA"
+    assert b.quantity == Decimal("2.25")
+    assert b.unit_price == Decimal("85.40")
+    assert b.date == datetime(2026, 4, 1)
+
+
+def test_html_notes_record_html_strategy() -> None:
+    a = parse_invest_engine_email(_load("html_two_orders.eml"))[0]
+    assert a.notes is not None
+    assert "html" in a.notes
+
+
+# -- CSV attachment body --
+
+
+def test_csv_attachment_parses_all_rows() -> None:
+    activities = parse_invest_engine_email(_load("csv_attachment.eml"))
+    assert len(activities) == 3
+    by_symbol = {a.symbol: a for a in activities}
+    assert by_symbol["VUAG"].quantity == Decimal("12.5")
+    assert by_symbol["VUAG"].unit_price == Decimal("63.21")
+    assert by_symbol["VUAG"].date == datetime(2025, 4, 2)
+    assert by_symbol["SWDA"].quantity == Decimal("4.75")
+    assert by_symbol["VUSA"].date == datetime(2025, 4, 4)
+    for a in activities:
+        assert a.activity_type is ActivityType.BUY
+        assert a.currency == "GBP"
+        assert a.account_id == "invest-engine-primary"
+        assert a.account_type is AccountType.ISA
+        assert a.notes is not None
+        assert "csv" in a.notes
+
+
+# -- graceful failure modes --
+
+
+def test_unparseable_email_returns_empty_list() -> None:
+    assert parse_invest_engine_email(_load("unparseable.eml")) == []
+
+
+def test_html_partial_match_returns_only_parseable_orders() -> None:
+    activities = parse_invest_engine_email(_load("html_partial_match.eml"))
+    assert len(activities) == 1
+    a = activities[0]
+    assert a.symbol == "VUAG"
+    assert a.quantity == Decimal("3.0")
+    assert a.unit_price == Decimal("61.25")
+    assert a.date == datetime(2026, 4, 15)