feat(balance,lua): convert corpses pile up near wall into slope

[scarf005]

Purpose of change (The Why)

• Nerf 2F spear cheese in an interesting way
• Lots of zombies dead in single tile gets amalgamated into corpse slope aka zlope that works like a ramp
• so 2F spear cheese won't be as effective
• zeds with bionics won't get merged to preserve loot

Describe the solution (The How)

• Add a BN Lua on_mon_death zlope check.
• Merge big wall-backed zombie corpse piles into a slow ramp terrain.
• Keep corpse qualification in Lua, with minimal bindings for faction and harvest entry checks.

Describe alternatives you've considered

• make them rot? currently there seems to be no terrain that decays/has half-life.
• make zeds died on zlope fall down to surrounding tiles for another zlope creation
• make zlope minable for rare loot? blob essense?

Testing

2026-03-18_00-58-58.mp4

Additional context

BN's reply to CleverRaven/Cataclysm-DDA#85753

Checklist

Mandatory

• I wrote the PR title in conventional commit format.
• I ran the code formatter.
• I linked any relevant issues using github keyword syntax like closes #1234 in Summary of the PR so it can be closed automatically.
• I've committed my changes to new branch that isn't main so it won't cause conflict when updating main branch later.

Optional

• This PR modifies lua scripts or the lua API.
  • I have added lua scope to the PR title.
  • I have added type annotations to functions so that it's safe and easy to maintain.
  • I have committed the output of deno task docs:gen so the Lua API documentation is updated.

[SYPIAC]

Big brain, now i can build my house out of zwalls

[AlecWhite]

Does the zlope have the items and bionics of the corpses it is composed of?
If no, I wouldn't like it, as it would be a form of atom smasher. So a to-do to keep the items and components of the corpses would be awesome.

Does the zlope get destroyed when the corpses rot into bones?
If not, can we add another to-do for that please?

[scarf005]

Does the zlope have the items and bionics of the corpses it is composed of?

zlope explicitly merges zombie corpses that lacks bionic as loot, therefore no for both points.

Does the zlope get destroyed when the corpses rot into bones? If not, can we add another to-do for that please?

currently the system doesn't seems to support decaying terrain but will create a new issue once this gets merged.

[WishDuck]

Terrain decay should be easy enough once #8073 is merged
Issue is we had no way to store time of creation so it would have been entirely random before

[chaosvolt]

* make them rot? currently there seems to be no terrain that decays/has half-life.

I'd probably say we need the ability for them to decay over time because regular corpses decay. Having a big pile of corpses automatically convert into permanent terrain might be annoying and tedious, as then the player probably has no option but to clean up manually if they want to get rid of it, when they'd otherwise have the option to just let them rot.

Not to mention, won't this also eliminate unpulped corpses that would otherwise get back up? Many players such as myself still don't mind playing with revification turned on, so this needs to be accounted for.

[chaosvolt]

Aight, I got pinged for review on the discord so I'll make it official. Vital prereqs for this to be a mainline feature:

1. Needs to be able to decay away, or else any corpse ramp has to be cleared up manually by the player, making them a nuisance.
2. Needs to not cause zombies to vanish into the ether or else this will be exploitable via eliminating corpses that would otherwise reanimate.

The second issue may require #8073 to be able to store what corpses compose it as data, perhaps? That way it can track if it should remove corpses from the terrain when they reanimate, whether to remove the ramp if too many bodies decay away or reanimate, and this would as a bonus fix the need to exclude bionic zombies from the ramp?