chore: Bump version to 0.4.0

Key fix: Orphan cleanup now skips Claude processes in valid Gas Town
tmux sessions (gt-*/hq-*), preventing false kills of witnesses,
refineries, and deacon during startup.

Updated all component versions:
- gt CLI: 0.3.1 → 0.4.0
- npm package: 0.3.0 → 0.4.0

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

.beads/config.yaml

@@ -62,12 +62,6 @@
 # - github.repo
 sync-branch: beads-sync
 
-# Gas Town custom types (bd-t5o8i)
-# These types are used by Gas Town infrastructure but are not core beads types.
-# They will be removed from beads built-in types (bd-find4) and configured here instead.
-types:
-  custom: "molecule,gate,convoy,merge-request,slot,agent,role,rig,event,message"
-
 # Cross-project dependencies (gt-o3is)
 # Maps project names to paths for external dependency resolution
 # Format: external:<project>:<capability> in bd dep commands