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>

internal/cmd/version.go

@@ -12,7 +12,7 @@ import (
 
 // Version information - set at build time via ldflags
 var (
-	Version = "0.3.1"
+	Version = "0.4.0"
 	// Build can be set via ldflags at compile time
 	Build = "dev"
 	// Commit and Branch - the git revision the binary was built from (optional ldflag)