fix: handle S3 key length limits by hashing long collection/key names

S3 has a maximum key length of 1024 bytes. This fix ensures that long
collection or key names are automatically hashed when they exceed safe
limits (500 bytes each), keeping the total S3 key under 1024 bytes
while maintaining uniqueness through hash suffixes.

- Import hash_excess_length utility from key_value.shared.utils.sanitize
- Add MAX_COLLECTION_LENGTH and MAX_KEY_LENGTH constants (500 bytes each)
- Update _get_s3_key() to hash collection and key names if they exceed limits
- Follows the same pattern used by MongoDB store for handling long names

Fixes test_long_collection_name test which was failing with KeyTooLongError.

Co-authored-by: William Easton <strawgate@users.noreply.github.com>

Author: github-actions[bot]

key-value/key-value-aio/src/key_value/aio/stores/s3/store.py

@@ -2,6 +2,7 @@
 from typing import TYPE_CHECKING, Any, overload
 
 from key_value.shared.utils.managed_entry import ManagedEntry
+from key_value.shared.utils.sanitize import hash_excess_length
 from typing_extensions import Self, override
 
 from key_value.aio.stores.base import (
@@ -12,6 +13,12 @@
 # HTTP status code for not found errors
 HTTP_NOT_FOUND = 404
 
+# S3 key length limit is 1024 bytes
+# We allocate space for collection, separator, and key
+# Using 500 bytes for each allows for the separator and stays well under 1024
+MAX_COLLECTION_LENGTH = 500
+MAX_KEY_LENGTH = 500
+
 try:
     import aioboto3
     from aioboto3.session import Session  # noqa: TC002
@@ -206,14 +213,21 @@ async def _setup(self) -> None:
     def _get_s3_key(self, *, collection: str, key: str) -> str:
         """Generate the S3 object key for a given collection and key.
 
+        S3 has a maximum key length of 1024 bytes. To ensure compliance, we hash
+        long collection or key names to stay within limits while maintaining uniqueness.
+
         Args:
             collection: The collection name.
             key: The key within the collection.
 
         Returns:
             The S3 object key in format: {collection}/{key}
         """
-        return f"{collection}/{key}"
+        # Hash collection and key if they exceed their max lengths
+        # This ensures the combined S3 key stays under 1024 bytes
+        safe_collection = hash_excess_length(collection, MAX_COLLECTION_LENGTH)
+        safe_key = hash_excess_length(key, MAX_KEY_LENGTH)
+        return f"{safe_collection}/{safe_key}"
 
     @override
     async def _get_managed_entry(self, *, key: str, collection: str) -> ManagedEntry | None: