feat(nginx): emit JSON access logs with request_id, org_id, workspace_id

Add a json_combined log_format to all CVM nginx configs so every inference
request is logged with the fields needed to join cloud-api spans in Datadog:

  request_id   – X-Request-Id header (set by cloud-api, part of e2e tracing)
  org_id       – X-Org-Id header (set by cloud-api PR #624)
  workspace_id – X-Workspace-Id header (set by cloud-api PR #624)
  host         – SNI hostname (identifies the model/CVM)
  method/uri   – request path
  status       – HTTP response code
  request_length / bytes_sent / request_time – cost/volume metrics
  upstream_addr – which inference-proxy instance handled the request

Datadog Agent already collects CVM logs with source:nginx; JSON escape=json
means fields are auto-parsed as @request_id, @org_id etc in Log Analytics
without any additional pipeline configuration.

Three files updated:
  - GLM-5.1.yaml       (per-server access_log directives, :80 + :443)
  - Qwen3.5-122B.yaml  (http-context access_log, flat config style)
  - small-models.yaml  (http-context access_log, flat config style)

Part of org-id e2e tracing plan (cloud-api#625).
Depends on: cloud-api#624 (MERGED), inference-proxy#130 (MERGED)

Author: Lloyd

GLM-5.1.yaml

@@ -269,9 +269,25 @@ configs:
       done
   nginx_conf:
     content: |
+      log_format json_combined escape=json
+        '{'  '"time":"$$time_iso8601"'
+        ',"request_id":"$$http_x_request_id"'
+        ',"org_id":"$$http_x_org_id"'
+        ',"workspace_id":"$$http_x_workspace_id"'
+        ',"host":"$$host"'
+        ',"method":"$$request_method"'
+        ',"uri":"$$uri"'
+        ',"status":$$status'
+        ',"request_length":$$request_length'
+        ',"bytes_sent":$$bytes_sent'
+        ',"request_time":$$request_time'
+        ',"upstream_addr":"$$upstream_addr"'
+        '}';
+
       server {
           listen 80 default_server;
 
+          access_log /var/log/nginx/access.log json_combined;
           client_max_body_size 100m;
           client_body_buffer_size 1m;
 
@@ -306,6 +322,7 @@ configs:
           keepalive_timeout 1h;
           keepalive_requests 1000000;
 
+          access_log /var/log/nginx/access.log json_combined;
           client_max_body_size 100m;
           client_body_buffer_size 1m;
 

Qwen3.5-122B.yaml

@@ -301,6 +301,23 @@ configs:
       done
   nginx_conf:
     content: |
+      log_format json_combined escape=json
+        '{'  '"time":"$$time_iso8601"'
+        ',"request_id":"$$http_x_request_id"'
+        ',"org_id":"$$http_x_org_id"'
+        ',"workspace_id":"$$http_x_workspace_id"'
+        ',"host":"$$host"'
+        ',"method":"$$request_method"'
+        ',"uri":"$$uri"'
+        ',"status":$$status'
+        ',"request_length":$$request_length'
+        ',"bytes_sent":$$bytes_sent'
+        ',"request_time":$$request_time'
+        ',"upstream_addr":"$$upstream_addr"'
+        '}';
+
+      access_log /var/log/nginx/access.log json_combined;
+
       proxy_http_version 1.1;
       proxy_set_header Host $$host;
       proxy_set_header X-Real-IP $$remote_addr;

small-models.yaml

@@ -910,6 +910,23 @@ configs:
       done
   nginx_conf:
     content: |
+      log_format json_combined escape=json
+        '{'  '"time":"$$time_iso8601"'
+        ',"request_id":"$$http_x_request_id"'
+        ',"org_id":"$$http_x_org_id"'
+        ',"workspace_id":"$$http_x_workspace_id"'
+        ',"host":"$$host"'
+        ',"method":"$$request_method"'
+        ',"uri":"$$uri"'
+        ',"status":$$status'
+        ',"request_length":$$request_length'
+        ',"bytes_sent":$$bytes_sent'
+        ',"request_time":$$request_time'
+        ',"upstream_addr":"$$upstream_addr"'
+        '}';
+
+      access_log /var/log/nginx/access.log json_combined;
+
       # Common proxy settings
       proxy_http_version 1.1;
       proxy_set_header Host $$host;