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.

Plugin/unraid/Tools/storage_migrate.sh

@@ -24,6 +24,29 @@
 #   varaverk.cron     rebuilt via PHP (job paths regenerated for new SCRIPTS_DIR)
 #
 # ==============================================================================================
+# DESIGN PRINCIPLES
+# ==============================================================================================
+#
+# Atomic Path Transition
+#   All four files (varaverk.cfg, master.conf, host*.conf, varaverk.cron) are
+#   updated in a single pass. A partial migration would leave cron entries
+#   pointing at the wrong SCRIPTS_DIR — all or nothing.
+#
+# PHP Rebuilds Cron
+#   Job paths in varaverk.cron are derived from SCRIPTS_DIR. Rather than
+#   text-substituting the cron file, the script regenerates it via PHP using
+#   the new SCRIPTS_DIR as the source of truth.
+#
+# ==============================================================================================
+# OPERATIONAL SAFEGUARDS
+# ==============================================================================================
+#
+#   acquire_lock    — prevents concurrent migration attempts
+#   dry-run mode    — shows all changes without touching any file
+#   --status mode   — reports current mode without requiring a target
+#   --to= required  — refuses to run without an explicit target mode
+#
+# ==============================================================================================
 # RUNTIME MODES
 # ==============================================================================================
 #