The feature request

Currently, there is no way to:

1. Reassign existing time entries to a different milestone - Once a time entry is created with (or without) a milestone, the milestone association cannot be changed. The tmpo edit command allows editing start/end times and descriptions, but not the milestone assignment.

2. Modify milestone start and end times - Milestone timestamps are set automatically when using tmpo milestone start and tmpo milestone finish, with no ability to adjust them afterward. This prevents including entries that fall outside the automatic milestone timeframe.

These limitations make it difficult to:

• Fix mistakes when entries are created without an active milestone
• Reorganize work retroactively into milestones
• Adjust milestone boundaries to accurately reflect project phases
• Include existing work in a newly created milestone

Proposed solution

Implement two new capabilities:

1. Entry Milestone Reassignment

Add milestone management to the tmpo edit command (or create a new command like tmpo entry set-milestone):

• Allow users to change the MilestoneName field on existing entries
• Provide options: assign to milestone, remove from milestone, or change milestone
• Show a list of available milestones for the current project
• The database already supports this via UpdateTimeEntry() at internal/storage/db.go:693