Refactoring of storage code:

1. Fix some bugs in local_storage
2. Refactor unit tests to not set Media.key explicitly (unless it's well-known beforehand, which it isn't)
3. Limit length of URL for 'url' type path_generator
4. Throw an error if 'save_to' of local storage is too long
5. A few other tidyups

src/auto_archiver/core/media.py

@@ -21,14 +21,13 @@ class Media:
     Represents a media file with associated properties and storage details.
 
     Attributes:
-    - filename: The file path of the media.
-    - key: An optional identifier for the media.
+    - filename: The file path of the media as saved locally (temporarily, before uploading to the storage).
     - urls: A list of URLs where the media is stored or accessible.
     - properties: Additional metadata or transformations for the media.
     - _mimetype: The media's mimetype (e.g., image/jpeg, video/mp4).
     """
     filename: str
-    key: str = None
+    _key: str = None
     urls: List[str] = field(default_factory=list)
     properties: dict = field(default_factory=dict)
     _mimetype: str = None  # eg: image/jpeg
@@ -67,6 +66,10 @@ class Media:
         # checks if the media is already stored in the given storage
         return len(self.urls) > 0 and len(self.urls) == len(in_storage.config["steps"]["storages"])
 
+    @property
+    def key(self) -> str:
+        return self._key
+
     def set(self, key: str, value: Any) -> Media:
         self.properties[key] = value
         return self