fix(docs): quote special characters in mermaid edge labels and resolve subgraph connections

docs/panduan_integrasi_existing_airflow.md

@@ -27,7 +27,7 @@ flowchart LR
         AF_SCHEDULER --- AF_DAG_PROC
     end
 
-    STANDALONE -.->|"Deploy DAG (Git / YAML)"| AIRFLOW_HOST
+    PIPES -.->|"Deploy DAG (Git / YAML)"| AF_DAG_PROC
     API -.->|"Direct Link Out"| AF_WEBSERVER
 ```
 
@@ -219,10 +219,10 @@ flowchart LR
         PG["PostgreSQL MetaDB\n(Port :5432 / Custom)"]
     end
 
-    BE -->|REST API :12082| AF_WEB
-    BE -->|Introspection & Safe Preview| PG
-    BE -->|Storage Connection| S3
-    AF_SCHED -.->|Eksekusi Task Ingestion| S3
+    BE -->|"REST API :12082"| AF_WEB
+    BE -->|"Introspection & Safe Preview"| PG
+    BE -->|"Storage Connection"| S3
+    AF_SCHED -.->|"Eksekusi Task Ingestion"| S3
 ```
 
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