[Anniversary] [th01] Debug: Define a constant length for the `bomb` v…

…ariable

6 halfwidth characters because it can potentially be signed. No more
confusing `timer` values!

Completes P0239, funded by Ember2528.

Merge branch "debloated" into anniversary

[Anniversary] [th01] Shootout lasers: Remove unblitting on reset

Freezing the lasers in place during the defeat animation is arguably
nicer than trying to unblit them, *and* we don"t need to work around
the graph_r_line() General Protection Fault!

Completes P0234, funded by Ember2528.