Implement Timestamp Micron Extension `T

[gmlewis]

gonomadnet added a new Micron extension for timetamps based on Python3's "strftime" function that enables timestamps to be rendered in the user's local timezone.

This PR adds this support to Columba. Timestamps look like this:

`T1789178907`T
`T1789178907|%F %T`T
`T<sec>|<format>`T

I have a guestbook WASM plugin that uses this feature that can be seen here:
c7d0e7bbd883e595f53e14fa6986188c:/page/guestbook.wasm

After installing this extension to Columba, it now renders like this:

[greptile-apps]

Confidence Score: 4/5

[Medium risk] Adds timestamp rendering to the markup parser.

Fix the week-number calculation before merging.

Findings

1.  Date formats appear as codes ▶

Fix with agent prompt

### Issue 1
micron/src/main/java/network/columba/app/micron/MicronTimestamp.kt:undefined-131
`expand` leaves standard Python `time.strftime` conversions such as `%c`, `%x`, `%X`, `%w`, `%U`, and `%W` unimplemented. For example, `` `T1789178907|%c`T `` displays the literal `%c` instead of a local date and time. This breaks the format language promised by this extension. Implement the missing standard conversions and add tests that distinguish them from genuinely unknown ones.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

Summary

Adds the Micron timestamp extension, which displays Unix seconds in the reader’s timezone.

• Micron pages can show Unix timestamps in the reader’s timezone.
• Timestamp formats can choose date, time, and timezone details.

_{Reviews (2) · Last reviewed commit: "Implement missing strftime format codes" · Reviewed by Greptile}

[torlando-tech]

@gmlewis Thanks for the PR. Have you considered submitting this syntax extension upstream to python nomadnet?

[gmlewis]

@gmlewis Thanks for the PR. Have you considered submitting this syntax extension upstream to python nomadnet?

Thank you, @torlando-tech - I would really like to do that, but I haven't yet figured out how to do that.

[gmlewis]

The really nice thing about the Python 3 implementation will be that they should hopefully be able to call strftime directly. 😂

[torlando-tech]

@gmlewis no guarantees but Mark interacts with the forum on https://rns.recipes/forum on a semi regular basis. You can also reach this via nomadnet at 9ce92808be498e9e05590ff27cbfdfe4:/page/index.mu

Either a post on this forum or an LXMF to Mark (you can find his address on any of his posts there) would be your best bet. Zenith has also contributed to nomadnet quite a bit in recent months.

The reason I bring this up is because the couple of times I have introduced extensions in the past resulted in other clients implementing their own versions of them and introducing fragmentation. I'd much prefer to get it upstream first if possible before merging into columba.

[torlando-tech]

@gmlewis a timely thread: https://rns.recipes/forum/general/how-do-i-raise-an-issue-on-nomadnet