fix(otelcol): use AccountID/ProjectID headers for VictoriaLogs multitenancy

로그 테넌트 라우팅이 동작하지 않던 결함 수정. otelcol exporter가
'VictoriaLogs-AccountID' 헤더를 사용했으나 VictoriaLogs는 이를 인식하지 못해
모든 로그가 account 0 으로 적재됨(dev 실측: AccountID:1 쓰기는 acct1,
VictoriaLogs-AccountID:1 쓰기는 acct0). 올바른 헤더 AccountID/ProjectID 로 교체.

- opentelemetry-collector custom-values(로그 3파이프라인) + events(acct0)
- docs: deploy-guide §1.4 relabel '[]'=격리아님 경고+예시, vmagent CUSTOM-README keep 규칙 예시
- .gitignore: tenant-verification/ (로컬 검증 산출물)

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

manifests/helm/opentelemetry-collector/0.156.2/custom-values-events.yaml

@@ -49,7 +49,8 @@ config:
       tls:
         insecure: true
       headers:
-        VictoriaLogs-AccountID: "0"
+        AccountID: "0"
+        ProjectID: "0"
 
   service:
     pipelines:

manifests/helm/opentelemetry-collector/0.156.2/custom-values.yaml

@@ -136,24 +136,29 @@ config:
           - 'IsMatch(attributes["namespace"], "^(demo01|demo02)-.*")'
 
   exporters:
+    # VictoriaLogs 멀티테넌시 헤더는 AccountID/ProjectID 다. (VictoriaLogs-AccountID는
+    # 인식되지 않아 전량 account 0 으로 적재됨 — dev 실측으로 확인. docs/victorialogs #multitenancy)
     otlphttp/vlogs-0:
       endpoint: "http://vlogs-victoria-logs-cluster-vlinsert.monitoring.svc.cluster.local:9481/insert/opentelemetry"
       tls:
         insecure: true
       headers:
-        VictoriaLogs-AccountID: "0"
+        AccountID: "0"
+        ProjectID: "0"
     otlphttp/vlogs-1:
       endpoint: "http://vlogs-victoria-logs-cluster-vlinsert.monitoring.svc.cluster.local:9481/insert/opentelemetry"
       tls:
         insecure: true
       headers:
-        VictoriaLogs-AccountID: "1"
+        AccountID: "1"
+        ProjectID: "0"
     otlphttp/vlogs-2:
       endpoint: "http://vlogs-victoria-logs-cluster-vlinsert.monitoring.svc.cluster.local:9481/insert/opentelemetry"
       tls:
         insecure: true
       headers:
-        VictoriaLogs-AccountID: "2"
+        AccountID: "2"
+        ProjectID: "0"
 
   service:
     pipelines: