chore: update simple-rpg configs for quality presets, regenerate audio assets

game.yaml / game_fast.yaml: switch to generation: quality preset model
instead of per-tool params; add paint/rig/animate/lod/collision stages
to manifest_goblin.yaml. Replace trimmed/regenerated WAV audio files
and add new SFX (chest_open, coin, collect, potion, step, sword_swing).

Author: maikramer