Give every NPC a race and class, resolved at spawn time

NPCs can now optionally specify race and class in their TOML. When
omitted, race is randomly selected from non-hidden races and class is
determined by the race's default_class or picked randomly from
compatible non-hidden classes. Race/class are re-rolled on each
respawn for NPCs without fixed values, so killing the barkeep may
bring back a different race next time.

New hidden content (excluded from character creation):
- Beast race: for animals (rats, etc.) with feral stats and no
  equipment slots
- Peasant class: weak default for humanoid NPCs
- Creature class: default for beasts/animals

Existing races gain default_class fields (humanoids → peasant,
beast → creature, dragon → random compatible). Look and examine
commands now display NPC race and class.

Made-with: Cursor

world/races/halfling.toml

@@ -1,5 +1,6 @@
 name = "Halfling"
 description = "Small and nimble, halflings slip through danger with uncanny luck."
+default_class = "class:peasant"
 
 [stats]
 strength = -2