Add structured headers to the PHP include layer, fix monitor state paths

All 16 include/ files now carry PURPOSE / DESIGN PRINCIPLES / OPERATIONAL
SAFEGUARDS / EXPORTS / CONFIGURATION, keeping the first three section names
identical to the bash headers so retrieval can route across both languages.

monitor.php read six watchdog state files from /tmp while the watchdogs write
to STATE_DIR, so every strike set came back empty and the summary reported
healthy unconditionally. docs.php gained path containment before it is wired
to a page.

Plugin/unraid/include/unraid_api.php

@@ -1,4 +1,48 @@
 <?php
+// ═══════════════════════════════════════════════════════════════════════════════════════════════
+// PURPOSE
+//   Unraid GraphQL API client. Issues one combined query per request for OS, CPU, memory,
+//   disks and array state, and records which callers had to fall back when the API is
+//   unavailable.
+//
+// DESIGN PRINCIPLES
+//   One round trip per request, not one per metric.
+//       vv_api_data() runs a single combined query and caches it for the lifetime of the
+//       request. A page reading eight metrics still makes one API call.
+//
+//   Fallback is expected, and it is tracked.
+//       The unraid-api registry is ephemeral — a key that worked yesterday can be gone.
+//       Every function that had to use a local path records itself via
+//       vv_api_record_fallback(), so vv_api_get_status() can report precisely which data is
+//       degraded rather than a single unhelpful "API down".
+//
+//   The API is an optimisation, never a dependency.
+//       Every value it provides has a local path in common.php. Losing the API costs detail
+//       and precision, not availability.
+//
+// OPERATIONAL SAFEGUARDS
+//   Absent or invalid key degrades silently to local reads.
+//       No exception, no error banner — the caller gets its value from /proc or sysfs and the
+//       fallback is recorded for the status endpoint.
+//
+//   Request-lifetime cache only.
+//       Nothing is persisted to disk here, so a stale API response cannot outlive the page
+//       that fetched it.
+//
+//   Read-only. Queries state; issues no mutations against unraid-api.
+//
+// EXPORTS
+//   vv_api_data()            the combined query result, cached per request
+//   vv_api_get_status()      availability plus the list of functions that fell back
+//   vv_api_record_fallback() called by consumers when they use a local path instead
+//   vv_api_node_metrics()    per-node metric summary
+//   vv_api_disk_entry()      normalised disk record
+//   vv_local_host_stats()    local summary in the same shape as a remote node
+//
+// CONFIGURATION
+//   HOST*_UNRAID_API_KEY   written every array start and every 15 min by
+//                          Plugin/unraid/System_Essentials/unraid_api_key_renew.sh
+// ═══════════════════════════════════════════════════════════════════════════════════════════════
 // Unraid GraphQL API — single-request master fetch + per-function fallback tracking.
 // All API-first functions call vv_api_data() then fall back to local reads on null.
 //