Timezone-aware output for age

[bbjubjub2494]

Component

Cast

Describe the feature you would like

cast age currently produces a timestamp in human-readable format that does not carry a timezone indication. This is ambiguous because it is implicitly in the UTC timezone, but other tools might assume that it is in a contextual local timezone. This can lead users to compute incorrect values — e.g. block timestamps that are off by one or more hour — in normal usage and can be very hard to debug. It would suffice to add " UTC" to the output to resolve this ambiguity.

Additional context

Say you want to compute the timestamp of the block at which that the merge happened on Mainnet on a Linux machine. You could combine Foundry with the standard date command to obtain that information. However, if your timezone is different than UTC (here Europe/Zurich), the naive command combination below will give an incorrect result. The two alternatives that follow give the correct result

$ date +%s -d "`cast age 15537394`"  # incorrect result
1663216979
$ date +%s -d "`cast age 15537394` UTC"  # simulating foundry-side fix
1663224179
$ date +%s -ud "`cast age 15537394`"  # ad-hoc fix
1663224179