- implement remove_label_from_rule function to delete labels from rules
- add error handling for rule not found
- save configuration after removing the label
- fix the logic of `remove_rule_by_label` to check label existence correctly
- change the error returned when label not found to include the label
- add log information when removing rules by id or label
- changed the type of the key used in the rules BTreeMap from usize to String
- this change makes it easier to serialize and deserialize the configuration
- updated the remove_rule_by_id and remove_rule_by_label functions to use string keys
- change rules storage from BTreeMap<String, EolRule> to BTreeMap<usize, EolRule>
- implement functions to remove rules by ID or label
- add helper functions to retrieve labels and rules associated with labels
- improve error handling for missing labels or rules
- allow retention rules to be configured to delete messages
- add `delete` flag to `add_rule` function
- add `set_command` function to `EolRule` to set the action to delete
- allow associating labels with retention rules for more granular control
- add label parameter to `add_rule` function
- check for duplicate rules and labels before adding new ones
- migrate rules from Vec to BTreeMap for efficient access
- add rule existence check to prevent duplicates
- improve rule listing by iterating over values
- add config.rs to handle program configuration
- create default configuration with retention rules
- implement save and load functions for persistent storage
- add credential file setting
