Pull Request Checklist

• I have read and followed the contribution guidelines.
• My pull request targets the main branch of tmpo.
• I have tested these changes locally on my machine.

Closes #48

Description

This pull request enhances the tmpo edit command by adding support for assigning or changing the milestone associated with a time entry. It introduces an interactive milestone selection step, provides user feedback if an entry's date falls outside the selected milestone's range, and updates the documentation to reflect these new capabilities.

Milestone assignment and validation:

• Added interactive milestone selection when editing an entry, allowing users to assign, change, or remove a milestone for the entry. The UI displays available milestones with their status (Active/Finished) and pre-selects the current milestone if present. (cmd/entries/edit.go)
• Implemented a warning prompt if the entry's date is outside the selected milestone's date range, giving users the option to proceed or cancel the assignment. (cmd/entries/edit.go)
• Updated the diff/confirmation view to show changes in milestone assignment alongside other field changes. (cmd/entries/edit.go)
• Included the milestone name in the editable fields of the entry data structure. (cmd/entries/edit.go)

Documentation updates:

• Updated the usage documentation to describe the new milestone assignment feature, including step-by-step instructions and explanations of date range warnings. (docs/usage.md) [1] [2]