restore-test wire contract: warnings + warnings_recognized in host-report golden (Phase B)

Adds the two new RestoreTest wire keys to the shared host-report golden and exercises
them in the bidirectional key-set contract test. Kept byte-identical with felhom-hub's
copy (sha256 e6999d77...). Testdata/tests only — the v0.7.0 binary is unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

internal/hub/contract_test.go

@@ -57,6 +57,10 @@ func TestHostReport_ContractMatchesGolden(t *testing.T) {
 			{
 				SourceArchive: "local:backup/x.tar.zst", SourceTier: "local", ScratchVMID: 990000,
 				Pass: true, Verified: "boot+running", TestedAt: "2026-06-09T11:05:00Z", DurationSeconds: 1,
+				// slice-7 (v0.7.0): warnings + warnings_recognized must appear in the marshaled
+				// shape so the bidirectional key-set guard exercises the new wire keys.
+				Warnings:           []string{"WARN: Systemd 257 detected. You may need to enable nesting."},
+				WarningsRecognized: true,
 			},
 		},
 		PBSSnapshots: []PBSSnapshot{

internal/hub/testdata/host-report.golden.json

@@ -108,7 +108,11 @@
       "pass": true,
       "verified": "boot+running",
       "tested_at": "2026-06-09T11:05:00Z",
-      "duration_seconds": 38.2
+      "duration_seconds": 38.2,
+      "warnings": [
+        "WARN: Systemd 257 detected. You may need to enable nesting."
+      ],
+      "warnings_recognized": true
     }
   ],
   "pbs_snapshots": [