Initial income_calculator project

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/parsers/base.py

@@ -0,0 +1,23 @@
+from abc import ABC, abstractmethod
+from dataclasses import dataclass
+from typing import List
+
+
+@dataclass
+class ParsedTransaction:
+    operation_date: str  # ISO date or datetime
+    debit_date: str | None
+    amount: float  # signed: negative = expense
+    amount_card_currency: float | None
+    description: str
+    card_tail: str  # last 4 digits for account matching
+
+
+class BaseBankParser(ABC):
+    @abstractmethod
+    def can_parse(self, filename: str) -> bool:
+        pass
+
+    @abstractmethod
+    def parse(self, file_path: str) -> List[ParsedTransaction]:
+        pass