Add unit tests for the time-ago formatter returning the correct human-readable string for various timestamp inputs

[Chucks1093]

Summary

The time-ago formatter converts a UTC timestamp to a human-readable string (e.g. '2 minutes ago', '3 days ago'). Unit tests should cover all time buckets and confirm the formatter handles future timestamps and the exact boundary values.

Scope

• Test a timestamp 30 seconds ago returns 'just now'
• Test a timestamp 5 minutes ago returns '5 minutes ago'
• Test a timestamp 2 hours ago returns '2 hours ago'
• Test a timestamp 3 days ago returns '3 days ago'
• Test a future timestamp returns 'just now' (no negative values)

Acceptance Criteria

• 30 seconds ago returns 'just now'
• 5 minutes ago returns '5 minutes ago'
• 2 hours ago returns '2 hours ago'
• 3 days ago returns '3 days ago'
• Future timestamp returns 'just now'

ETA: 12 hours

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