Enable Querying Recent Propositions

[XenonMolecule]

This pull request introduces a new feature to list the most recent propositions from the database, along with supporting changes to the CLI and backend. The main changes include adding a --recent or -r CLI flag, implementing the backend logic to fetch recent propositions, and updating the application flow to support this new mode.

CLI and User Experience Improvements:

• Added a --recent (-r) flag to the CLI in gum/cli.py to allow users to list the most recent propositions instead of running a BM25 search. The help message and argument parsing were updated accordingly.
• Updated the main CLI logic to support the new --recent mode, including user guidance and output formatting for recent propositions.

Backend and Data Access Enhancements:

• Implemented the get_recent_propositions async function in gum/db_utils.py to fetch the most recent propositions from the database, with options for limiting results and filtering by time range.
• Added a recent method to the gum class in gum/gum.py to expose the recent propositions functionality to the application layer.
• Imported the new get_recent_propositions function in gum/gum.py to enable its use in the recent method.

[XenonMolecule]

• Implemented get_recent_observations async functions in db_utils.py to fetch the most recent propositions and observations from the database, supporting optional time bounds and eager loading of related observations.
• Added recent_observations async methods to the gum class to expose the new database utilities at the application level.
• Updated imports in gum.py to include the new database utility functions.

[oshaikh13]

as always, great stuff michael ryan