feat: wall-climbing monsters

[shmakota]

Purpose of change (The Why)

It feels insanely weird giant spiders, ants, and similar creatures can't crawl up the wall after me. Also helps solve spear cheese a bit.

Describe the solution (The How)

Add a new "CLIMBS_WALLS" flag which allows the monster to climb up walls and onto ceilings.

Adds the flag to:
spiderbots
all spiders
spideer
all ants
new clinger crawler zombie
predator zombie

Describe alternatives you've considered

Allowing the normal crawler to climb up walls? Think it's best to limit this past an evolutionary stage so the first days are still generally safe for spear cheese.

Testing

Spawn at a high location (silo, office tower, etc). Silo works well for this because it has solid walls that can't be broken, and the zombies can still see you on top. Spawn a horde of "clinger crawlers" and note as they start ascending the walls to get to you.

Additional context

Probably need to ensure they vertically climb in a reasonable amount of time.

2026-02-25.13-03-14.mp4

Checklist

Mandatory

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[autofix-ci]

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