Document the api layer's operational models, and fix two headers that had gone stale against the code

Plugin/unraid/api/partnership.php

@@ -5,6 +5,16 @@
 //   reachability, SSH trust, conf-sync state and the shared-service inventory — for the
 //   partnership tab's poll.
 //
+// OPERATIONAL MODEL
+//   One call, one document. The endpoint holds no logic and adds no cache of its own — it
+//   encodes whatever vv_partnership_all() returns, so any freshness policy is the library's and
+//   there is only one place it can be changed.
+//
+//   The whole picture is assembled per request rather than exposed as separate endpoints for
+//   hosts, trust and services. Those answers are read together and judged against each other —
+//   a host that is reachable but has lost SSH trust is a different state from either fact alone,
+//   and splitting them would let the tab render a combination that never existed at one moment.
+//
 // DESIGN PRINCIPLES
 //   Thin transport. Host enumeration, SSH probing and trust evaluation live in
 //   include/partnership.php; this file only sets the content type and encodes.