Add full banner headers to all scripts across the codebase

Every script now has the established header format: PURPOSE with ─────── separator,
OPERATIONAL MODEL, DESIGN PRINCIPLES, OPERATIONAL SAFEGUARDS, CONFIGURATION, and
RUNTIME MODES — structured with full ====== banner sections throughout.

Orchestrators converted from compact ── inline format to full banners. Stale
emby-fallback and dirty sync references removed from Plugin/user_script_plug-in.sh.

Media/lidarr_cleanup.sh

@@ -27,6 +27,25 @@
 # classification these would be deleted — breaking Lidarr and Emby display.
 #
 # ==============================================================================================
+# DESIGN PRINCIPLES
+# ==============================================================================================
+#
+# API as Ground Truth
+#   What Lidarr tracks is authoritative. Files not in the API response are
+#   orphans — Lidarr has no record of them and they serve no purpose.
+#   The script never infers ownership from directory structure alone.
+#
+# Age Gate Before Deletion
+#   Files under LIDARR_ORPHAN_AGE are left alone regardless of tracked status.
+#   Lidarr's import pipeline writes files before registering them — acting
+#   immediately would delete files mid-import.
+#
+# Seven-Gate Safety Model
+#   Multiple independent sanity checks must all pass before any file is touched.
+#   No single check is trusted in isolation — a misconfigured path returning an
+#   empty API response must not result in a wiped library.
+#
+# ==============================================================================================
 # OPERATIONAL SAFEGUARDS
 # ==============================================================================================
 #