Ship production optimization M1-M12.5A: queues, metrics, HTTP observability, and vector search reliability.

Keep similar-ai from tripping the global circuit on a lone URL 502, clamp Qdrant search to 100, and add Server-Timing plus slow-request logging. Studio shared props, Academy S3 exists caching, heat chunking, and Redis/scheduler hygiene stay in this rollout.

deploy/nginx/conf.d/skinbase-perf-log-format.conf

@@ -0,0 +1,23 @@
+# M12 — structured HTTP performance log format.
+# Install into /etc/nginx/conf.d/ (already included from nginx.conf http {}).
+# Do not replace the existing combined access log.
+# Activate with a second access_log on the Skinbase server block.
+#
+# Variables validated against nginx/1.26.3 on server3.
+# $uri is used (not $request_uri) so query strings are not logged.
+# No $remote_addr, cookies, or Authorization.
+
+log_format skinbase_perf escape=json
+    '{"time":"$time_iso8601",'
+    '"host":"$host",'
+    '"method":"$request_method",'
+    '"uri":"$uri",'
+    '"status":$status,'
+    '"request_time":$request_time,'
+    '"upstream_response_time":"$upstream_response_time",'
+    '"upstream_connect_time":"$upstream_connect_time",'
+    '"upstream_header_time":"$upstream_header_time",'
+    '"bytes":$body_bytes_sent,'
+    '"request_length":$request_length,'
+    '"content_type":"$sent_http_content_type",'
+    '"cache":"$upstream_cache_status"}';