Improve readability of version id

[nameOfUser0236]

The version id that particleos currently uses is difficult to read, especially at a glance.
ParticleOS_20260407090321
ParticleOS_20260402165858
ParticleOS_20260425133700
As seen above, the numbers jumble together, resulting in it being difficult to tell which one is first, second... etc.

There are several formats to fix this, sacrificing varying amounts of length for readability. I would like to hear your thoughts on which one you think is best.

1. ParticleOS_YYYYmmdd-HHMMSS
2. ParticleOS_YYYYmmdd-HH.MM.SS
3. ParticleOS_YYYY.mm.dd-HH.MM.SS
4. ParticleOS_YYYY.mm.dd-HH:MM:SS

Note: This is something that is difficult to change after install, so having a sensible default is important.

(the above examples with actual dates for reference)

1. ParticleOS_20260407-091708
2. ParticleOS_20260407-09.17.08
3. ParticleOS_2026.04.07-09.17.08
4. ParticleOS_2026.04.07-09:17:08

[nameOfUser0236]

I get the following error when I implement this change:
/work/<path...>/mkosi.repart/10-usr-verity-sig.conf:5: Failed to expand specifiers in Label=, ignoring: %M_%A_verity_sig
I have tried the following version id's in mkosi.bump: date +%Y%m%d-%H%M%S date +%Y%m%d_%H%M%S date +%Y%m%d0%H%M%S

inspecting the resulting image with fdisk gives the following output:

fdisk -l -o Name,Type,Type-UUID,Size mkosi.output/ParticleOS_20260411_121758_x86-64

Disk mkosi.output/ParticleOS_20260411_121758_x86-64: 2.31 GiB, 2485661696 bytes, 4854808 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: gpt
Disk identifier: 55F20ECA-CA4F-4E71-87CC-B82E1FBA1B86

Name                              Type                             Type-UUID                              Size
esp                               EFI System                       C12A7328-F81F-11D2-BA4B-00A0C93EC93B     1G
usr-x86-64-verity-sig             Linux /usr verity sign. (x86-64) E7BB33FB-06CF-4E81-8273-E543B413E2E2    16K
ParticleOS_20260411_121758_verity Linux /usr verity (x86-64)       77FF5F63-E7B6-4633-ACF4-1565B864C0E6   400M
ParticleOS_20260411_121758        Linux /usr (x86-64)              8484680C-9521-48C6-9C11-B0720656F69E 945.5M

Note that only the verity signature partition is affected.
This breaks systemd-gpt-auto-generator.

[nameOfUser0236]

After some testing, it appears that while the GPT partition table uses 72 bytes to store the partition name, in can only store 36 chars (two bytes per char). ParticleOS_YYYYmmddHHMMSS_verity_sig is 36 chars long so the addition of a separator exceeds this limit. Manually changing it to use 1 byte per char with a hex editor breaks fdisk and gdisk, and likely other tools as well.