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.

Monitors/weekly_health_digest.sh

@@ -14,6 +14,24 @@
 # into a single digest. Reads only — writes nothing, changes nothing.
 #
 # ==============================================================================================
+# DESIGN PRINCIPLES
+# ==============================================================================================
+#
+# Aggregator, Not Generator
+#   This script reads state files that other scripts maintain. It never produces
+#   health data itself — it only presents what is already there. Each source
+#   script remains responsible for its own state; this script is the envelope.
+#
+# Profile-Driven Notification
+#   The cron schedule never changes. The DIGEST_PROFILE in master.conf controls
+#   when notifications actually send — switching from daily noise to weekly
+#   summaries is a one-line conf change, not a cron edit.
+#
+# Read-Only, No Side Effects
+#   Writes nothing, changes nothing, triggers nothing. Safe to run at any time
+#   for a health snapshot without affecting any running service or state file.
+#
+# ==============================================================================================
 # OPERATIONAL MODEL
 # ==============================================================================================
 #