fix(tui): handle tea.InterruptMsg for proper Ctrl+C cancellation

Bubbletea v1.3+ sends InterruptMsg for SIGINT signals instead of
KeyMsg with 'ctrl+c', causing cancellation to not work properly.

- Add tea.InterruptMsg handling to restore_exec.go
- Add tea.InterruptMsg handling to backup_exec.go
- Add tea.InterruptMsg handling to menu.go
- Call cleanup.KillOrphanedProcesses on all interrupt paths
- No zombie pg_dump/pg_restore/gzip processes left behind

Fixes Ctrl+C not working during cluster restore/backup operations.

v3.42.50

main.go

@@ -16,7 +16,7 @@ import (
 
 // Build information (set by ldflags)
 var (
-	version   = "3.42.49"
+	version   = "3.42.50"
 	buildTime = "unknown"
 	gitCommit = "unknown"
 )