feat(eval): add evidence pipeline acceptance closure

mvp/eval/cases/diagnosis-cases.json

@@ -1,4 +1,40 @@
 [
+  {
+    "id": "narrow-highcpu-observation",
+    "title": "Narrow HighCPU observation",
+    "question": "确认 payment-service 当前是否存在 HighCPUUsage 告警。",
+    "traceFixture": "narrow-highcpu-observation-pass.json",
+    "expectedRootCauseKeywords": ["payment-service", "HighCPUUsage", "92%"],
+    "minKeywordMatches": 2,
+    "requiredEvidenceTools": ["query_metrics"],
+    "allowedVerdicts": ["PASS"],
+    "forbiddenAnswerKeywords": ["根因", "修复建议", "通常情况下"],
+    "requireV2AuditClosure": true,
+    "requireClaimChecks": true,
+    "requireComposerOutput": true,
+    "expectedGatekeeperStatuses": ["pass"],
+    "expectedGatekeeperRuleSetVersion": "gatekeeper-rules-v1",
+    "expectedComposerStatuses": ["valid"],
+    "forbiddenConfirmedClaimKeywords": ["数据库连接池"]
+  },
+  {
+    "id": "hikari-no-evidence-negative-observation",
+    "title": "Hikari no-evidence negative observation",
+    "question": "确认 inventory-service 当前是否有 HikariCP 连接池耗尽日志。",
+    "traceFixture": "hikari-no-evidence-negative-observation-pass.json",
+    "expectedRootCauseKeywords": ["未检索到", "HikariCP", "匹配证据"],
+    "minKeywordMatches": 2,
+    "requiredEvidenceTools": ["query_logs"],
+    "allowedVerdicts": ["PASS"],
+    "forbiddenAnswerKeywords": ["已排除", "确认没有", "日志层面已排除"],
+    "requireV2AuditClosure": true,
+    "requireClaimChecks": true,
+    "requireComposerOutput": true,
+    "expectedGatekeeperStatuses": ["pass"],
+    "expectedGatekeeperRuleSetVersion": "gatekeeper-rules-v1",
+    "expectedComposerStatuses": ["valid"],
+    "forbiddenConfirmedClaimKeywords": ["已排除 HikariCP"]
+  },
   {
     "id": "payment-timeout",
     "title": "Payment API timeout",