core: add snappy and tests

src/lean_spec/snappy/__init__.py

@@ -0,0 +1,41 @@
+"""Pure Python Snappy compression library.
+
+Snappy is a fast compression/decompression algorithm developed by Google.
+It prioritizes speed over compression ratio, making it ideal for real-time
+applications and network protocols.
+
+Usage::
+
+    from lean_spec.snappy import compress, decompress
+
+    # Compress data before sending
+    compressed = compress(data)
+
+    # Decompress received data
+    original = decompress(compressed)
+
+The implementation follows the Snappy format specification:
+https://github.com/google/snappy/blob/main/format_description.txt
+"""
+
+from __future__ import annotations
+
+from .compress import compress, max_compressed_length
+from .decompress import (
+    SnappyDecompressionError,
+    decompress,
+    get_uncompressed_length,
+    is_valid_compressed_data,
+)
+
+__all__ = [
+    # Core API
+    "compress",
+    "decompress",
+    # Utilities
+    "max_compressed_length",
+    "get_uncompressed_length",
+    "is_valid_compressed_data",
+    # Exceptions
+    "SnappyDecompressionError",
+]