20260727 修复缓存回放丢失reject reason（#132）：缓存artifact增加reject_reason字段，fresh验证记录真实原因，VCIR/PP cache回放还原，旧缓存给后备文案

tests/test_ccr_m7.rs

@@ -244,6 +244,7 @@ fn verify_against_vcir_store_matches_manifest_hashes() {
             sha256: manifest_hash.clone(),
             object_type: Some("mft".to_string()),
             validation_status: VcirArtifactValidationStatus::Accepted,
+            reject_reason: None,
         }],
         summary: VcirSummary {
             local_vrp_count: 0,

tests/test_manifest_processor_m4.rs

@@ -109,6 +109,7 @@ fn store_validated_manifest_baseline(
             sha256: manifest_sha256,
             object_type: Some("mft".to_string()),
             validation_status: VcirArtifactValidationStatus::Accepted,
+            reject_reason: None,
         }],
         summary: VcirSummary {
             local_vrp_count: 0,

tests/test_manifest_processor_repo_sync_and_cached_snapshot_cov.rs

@@ -112,6 +112,7 @@ fn store_validated_manifest_baseline(
             sha256: manifest_sha256,
             object_type: Some("mft".to_string()),
             validation_status: VcirArtifactValidationStatus::Accepted,
+            reject_reason: None,
         }],
         summary: VcirSummary {
             local_vrp_count: 0,