Add formatters module

src/contextgen/formatters/base.py

@@ -0,0 +1,24 @@
+"""Base formatter class for output formatting."""
+
+from abc import ABC, abstractmethod
+from pathlib import Path
+from typing import Any
+
+
+class BaseFormatter(ABC):
+    """Base class for all formatters."""
+
+    def __init__(self, output_path: Path | None = None):
+        self.output_path = output_path
+
+    @abstractmethod
+    def format(self, data: dict[str, Any]) -> str:
+        """Format data and return as string."""
+        pass
+
+    def save(self, data: dict[str, Any]) -> None:
+        """Format data and save to output path."""
+        if self.output_path:
+            self.output_path.parent.mkdir(parents=True, exist_ok=True)
+            content = self.format(data)
+            self.output_path.write_text(content, encoding="utf-8")