fix(config): correct Critters and Companions spawn keys to snake_case

YACL serialises config with FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES
(and serializeNulls), so the camelCase keys biomeSpec, leafInsect, seaBunny,
stagBeetle, rolyPoly and stickBug were never read. Every SpawnEntry then
deserialised with biomeSpec = null, and CAC 2.7.0's SpawnEntry.isTag() calls
biomeSpec.startsWith("#") without a null check, crashing FMLCommonSetup on
both the dedicated server and the client.

Rename the keys; all tuned weights and biome specs are unchanged. Missing
keys still fall back to mod defaults (partial file). Refresh the index and
pack hashes.

index.toml

@@ -10,7 +10,7 @@ hash = "bc47ee67032ceab8b2b408819ce9b268812f37da8f13b9b7efeae0deed607c4b"
 
 [[files]]
 file = "config/crittersandcompanions-common.json5"
-hash = "a00a9fe09ce5b469247f757e780b5faf74191f5cfef158d999c4d7a1e203f420"
+hash = "1ac5a9b392b3aa980abe86b37aa8a9853e91c02cd18f8a1bceea0d08fe3f10c4"
 
 [[files]]
 file = "config/defaultoptions/extra/config/DistantHorizons.toml"