AAP-72950: Fix EE image pull destination in network ports table and diagrams

Execution nodes pull EE images through the Gateway proxy, not directly
from Automation Hub. Verified against aap-containerized-installer source:
- execution_environments.py.j2 registers Hub EE images with Gateway URL
- upload_images.yml pushes images to Hub via Gateway proxy

Changes:
- Table: changed destination from Hub to Gateway for execution node
  EE image pull row, updated description to clarify proxy flow
- Diagrams: regenerated all 3 architecture diagrams with corrected
  Execution node → Gateway connection (was Execution node → Hub)
- Added .drawio source files for future diagram maintenance

Author: jklech-work

downstream/images/Container-network_internally_initiated.drawio

@@ -33,7 +33,7 @@ The following table shows container-based installation ports and inventory varia
 | {HubNameStart} | 80/443 | Installer node | TCP | HTTP/HTTPS | Enables installer node to push the execution environment image to automation hub when using the bundle installer. | ansible_port
 | {HubNameStart}  | 80/443 | {ControllerNameStart} | TCP | HTTP/HTTPS | Pull collections |
 | {HubNameStart} | 80/443 | {EDAName} node | TCP | HTTP/HTTPS | Pull container decision environments |
-| {HubNameStart} | 80/443 | Execution node | TCP | HTTP/HTTPS | Allows execution nodes to pull the execution environment image from {HubName} |
+| {GatewayStart} | 80/443 | Execution node | TCP | HTTP/HTTPS | Allows execution nodes to pull the execution environment image from {HubName} through {Gateway} |
 | {HubNameStart} | 80/443| Gateway load balancer/Ingress node | TCP | HTTP/HTTPS | Accessing the component directly from {Gateway} | automationgateway_main_url
 
 *gateway_main_url*