Reassign chores between users from the dashboard

[eemersonrosa]

Enhancement

Allow a chore to be reassigned to another person directly from the main dashboard, without opening settings or editing the chore.

Proposed behavior

Each per-chore row gains two controls:

• a check / undo button to mark the chore done (unchanged behavior), and
• a swap-arrow button that opens a dropdown to move the chore to a different user.

Keeping the daily bonus consistent

Reassignment respects the daily "all regular chores done" bonus:

• The award logic is extracted into a reusable helper and re-run for both the previous and the new owner on every move.
• A user who becomes all-done because a chore was moved still gets the bonus they earned.
• It never removes points, so no one loses score when a chore is moved.

Housekeeping

• gitignore the local SQLite database (server/data/tasks.db) and the generated encryption key
• stop tracking the previously-committed server/data/tasks.db

Implementation

A pull request implementing this is up for review: #110