refactor(trace): enforce run-only diagnosis model

mvp/eval/fixtures/audit-metadata-low-confid.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-audit-metadata-low-confid",
     "query": "订单超时是否可以确认由数据库主库故障导致，并检查审计元数据是否完整？",
     "status": "SUCCESS",

mvp/eval/fixtures/composer-fallback-no-raw-json-low-confid.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-composer-fallback-no-raw-json",
     "query": "库存服务慢响应是否可以直接输出 Executor JSON？",
     "status": "SUCCESS",

mvp/eval/fixtures/gatekeeper-fabricated-invocation-reject.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-gatekeeper-fabricated-invocation",
     "query": "支付失败是否能确认由日志中的连接池耗尽导致？",
     "status": "SUCCESS",

mvp/eval/fixtures/hikari-no-evidence-negative-observation-pass.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-hikari-no-evidence-negative-observation",
     "query": "确认 inventory-service 当前是否有 HikariCP 连接池耗尽日志。",
     "status": "SUCCESS",

mvp/eval/fixtures/jvm-memory-risk-low-confid.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-jvm-memory-risk",
     "query": "订单服务内存使用率过高，请判断是否存在 OOM 风险。",
     "status": "SUCCESS",

mvp/eval/fixtures/mysql-pool-low-confid.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-mysql-pool",
     "query": "订单服务大量请求超时，请判断是否和 MySQL 连接池有关。",
     "status": "SUCCESS",

mvp/eval/fixtures/narrow-highcpu-observation-pass.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-narrow-highcpu-observation",
     "query": "确认 payment-service 当前是否存在 HighCPUUsage 告警。",
     "status": "SUCCESS",

mvp/eval/fixtures/payment-timeout-pass.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-payment-timeout",
     "query": "支付接口最近出现超时，请结合知识库、日志和指标判断可能原因，并给出修复建议。",
     "status": "SUCCESS",

mvp/eval/fixtures/prompt-gatekeeper-audit-closure-pass.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-prompt-gatekeeper-audit-closure",
     "query": "确认 payment-service 当前是否存在 HighCPUUsage 告警，并检查审计元数据是否完整。",
     "status": "SUCCESS",

mvp/eval/fixtures/redis-timeout-low-confid.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-redis-timeout",
     "query": "支付服务出现 Redis 连接超时，请定位可能原因。",
     "status": "SUCCESS",

mvp/eval/fixtures/slow-response-pass.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-slow-response",
     "query": "用户服务 P99 响应时间升高，请结合指标和日志分析。",
     "status": "SUCCESS",

mvp/eval/fixtures/unsupported-claim-filtering-low-confid.json

@@ -1,5 +1,5 @@
 {
-  "session": {
+  "run": {
     "sessionId": "eval-unsupported-claim-filtering",
     "query": "订单超时是否可以确认由数据库主库故障导致？",
     "status": "SUCCESS",