R-85 Phase 1: the restore-test spec is built PER RUN, not frozen at daemon start

SchedulerOptions.Spec was a VALUE produced by an immediately-invoked function
at daemon start, so storageTier() and restoreTaskTimeout() were evaluated once
and reused for every run for the process lifetime. Nothing tier-varying was
expressible (the offsite tier could never be scheduled), and it was a latent
staleness bug besides: a storage-type or config change did not take effect
until restart.

- backup.SpecBuilder: func(ctx, archive) RestoreTestSpec, called once per run.
  The archive is passed because the tier MUST come from it (v0.100.0 rule) —
  config-derived is what classified a PBS archive as 'local' and killed a
  14.46 GB WAN restore at the 10-minute local bound.
- A nil spec builder SKIPS loudly instead of panicking: a wiring bug must cost a
  restore-test, never the daemon goroutine.

Red-proof observed. Full suite green (29 packages, rc=0).

cmd/felhom-agent/main.go

@@ -1247,8 +1247,19 @@ func buildRestoreTestScheduler(cfg config.Config, px *proxmox.Client, engine *re
 		Runner: engine,
 		Pick:   runner.PickRestoreCandidate,
 		Store:  store,
-		Spec: func() reconcile.RestoreTestSpec {
-			tier := storageTier(context.Background(), px, target)
+		// R-85 (1.1): the spec is built PER RUN, from the archive that was picked.
+		//
+		// This used to be an immediately-invoked function, so storageTier() and
+		// restoreTaskTimeout() ran ONCE at daemon start and their result was reused for every run
+		// forever. That froze the tier — and with it the timeout — making an offsite restore-test
+		// impossible to schedule, and leaving any storage-type or config change stale until the
+		// daemon restarted.
+		//
+		// The tier comes from the ARCHIVE (restoreTierForArchive, the v0.100.0 rule), never from
+		// the configured target: config-derived was what classified a PBS archive as "local" and
+		// killed a 14.46 GB WAN restore at the 10-minute local bound.
+		Spec: func(ctx context.Context, archive string) reconcile.RestoreTestSpec {
+			tier := restoreTierForArchive(ctx, px, archive, target)
 			return reconcile.RestoreTestSpec{
 				RestoreStorage:     cfg.Backup.RestoreStorage,
 				ScratchMin:         min,
@@ -1256,7 +1267,7 @@ func buildRestoreTestScheduler(cfg config.Config, px *proxmox.Client, engine *re
 				SourceTier:         tier,
 				RestoreTaskTimeout: restoreTaskTimeout(cfg, tier),
 			}
-		}(),
+		},
 		Cadence: cadence,
 		Logger:  logger,
 	})