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>

npm-package/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@gastown/gt",
-  "version": "0.3.0",
+  "version": "0.4.0",
   "description": "Gas Town CLI - multi-agent workspace manager with native binary support",
   "main": "bin/gt.js",
   "bin": {