Feature: display banner only on the first run

[cereda]

Hopefully a better understanding of #39. 😉

Added --one-time-banner to jbundle. When present, the underlying wrapper will use the app_hash string to look for a file of the same name inside ${HOME}/.jbundle/runs. During the first app run, this file does not exist, so the banner is displayed as expected, and the file is created. Subsequent runs will check for the file, and since it exists, the banner will be omitted.

I need some coffee now. ☕ 🦆

[cereda]

Clippy works locally, so I blame GH's CI. 😅

[avelino]

Clean implementation, follows the existing compact_banner pattern. A few points before merge:

Tests

• Missing test for happy path: one_time_banner = true generating stub with JBUNDLE_RUNS and [ ! -e ... ] logic
• Missing test for default case: one_time_banner = false not containing JBUNDLE_RUNS
• Missing test for compact_banner = true + one_time_banner = true combination

Cleanup of ~/.jbundle/runs/

This directory will accumulate marker files indefinitely. At minimum document this, ideally clean up alongside jbundle clean.

Race condition

If two instances of the same binary run in parallel for the first time, both pass the [ ! -e ... ] check before the touch. Banner shows up twice. No need to fix now, but document as a known limitation