chore: Bump version to 0.2.6

Updated all component versions:
- gt CLI: 0.2.5 → 0.2.6
- npm package: 0.2.5 → 0.2.6

Highlights:
- Unified escalation system with severity levels and routing
- gt stale command for binary staleness checks
- Per-agent-type health tracking in statusline
- Refactored sling.go into 7 focused modules
- Many bug fixes for beads, sling, and session lifecycle

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 = "0.2.5"
+	Version = "0.2.6"
 	// Build can be set via ldflags at compile time
 	Build = "dev"
 	// Commit and Branch - the git revision the binary was built from (optional ldflag)