v0.60.0: proof-of-launch destroy gating (F1a/b/c) + restore-test band-advance (F2)

Campaign pool-effects F1 (HIGH): the bring-up compensating rollback and the
restore-test teardown destroyed the target vmid even when RestoreLXC failed
synchronously without creating anything — destroying a guest the transaction
never made (only the pool ACL 403 contained it). A RestoreLXC UPID is now the
sole destroy authorization in all three destroy paths (in-process bring-up
defer, in-process restore-test teardown, Recover). F2: the restore-test
advances past an 'already exists' band vmid (invisible squatter) instead of
failing + false-alerting; a fully-occupied band Skips.

Red-proof verified: with the gates reverted, the four new tests fail with the
innocent-guest destroy. go build/vet/test clean.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

cmd/felhom-agent/main.go

@@ -45,7 +45,7 @@ import (
 
 // version is the agent version. Overridable at build time with
 // -ldflags "-X main.version=<v>"; defaults to the in-repo CHANGELOG version.
-var version = "0.59.0"
+var version = "0.60.0"
 
 // runGuestHook is the PVE pre-start hook body (`felhom-agent guest-hook <vmid> <phase>`). On the
 // pre-start phase it creates placeholder dirs for any absent bind-mount source so the guest always boots