* feat: add chunking mode for outbound messages
- Introduced `chunkMode` option in various account configurations to allow splitting messages by "length" or "newline".
- Updated message processing to handle chunking based on the selected mode.
- Added tests for new chunking functionality, ensuring correct behavior for both modes.
* feat: enhance chunking mode documentation and configuration
- Added `chunkMode` option to the BlueBubbles account configuration, allowing users to choose between "length" and "newline" for message chunking.
- Updated documentation to clarify the behavior of the `chunkMode` setting.
- Adjusted account merging logic to incorporate the new `chunkMode` configuration.
* refactor: simplify chunk mode handling for BlueBubbles
- Removed `chunkMode` configuration from various account schemas and types, centralizing chunk mode logic to BlueBubbles only.
- Updated `processMessage` to default to "newline" for BlueBubbles chunking.
- Adjusted tests to reflect changes in chunk mode handling for BlueBubbles, ensuring proper functionality.
* fix: update default chunk mode to 'length' for BlueBubbles
- Changed the default value of `chunkMode` from 'newline' to 'length' in the BlueBubbles configuration and related processing functions.
- Updated documentation to reflect the new default behavior for chunking messages.
- Adjusted tests to ensure the correct default value is returned for BlueBubbles chunk mode.
