feat: add notify scripts for state transitions

- Add notify_master/notify_backup/notify_fault support
- Support both file path and inline shell script
- Async execution with 60s timeout
- Inject GO_ALIVED_INSTANCE and GO_ALIVED_EVENT env vars
- Bump version to 1.3.0

🤖 Generated with [Qoder][https://qoder.com]

internal/cmd/root.go

@@ -7,7 +7,7 @@ import (
 )
 
 // Version can be set at build time via ldflags
-var Version = "1.2.1"
+var Version = "1.3.0"
 
 var rootCmd = &cobra.Command{
 	Use:   "go-alived",