Bring script headers onto the template and close safeguard gaps

Headers claimed protections the code never had, and several destructive paths had no
guard against a collapsed config value.

System_Essentials/clear_logs.sh

@@ -16,9 +16,33 @@
 # SABnzbd) grow fastest — inactive containers typically remain small.
 #
 # ==============================================================================================
+# OPERATIONAL MODEL
+# ==============================================================================================
+#
+# Two independent passes, each with its own threshold:
+#
+#   System logs — every path in LOG_FILES
+#     size < LOG_MIN_SIZE_MB    → skip, recent diagnostic history is worth keeping
+#     size >= LOG_MIN_SIZE_MB   → truncate in place
+#
+#   Docker logs — /var/lib/docker/containers/**/*-json.log
+#     container name resolved for reporting via docker inspect
+#     size < LOG_DOCKER_MAX_MB  → skip
+#     size >= LOG_DOCKER_MAX_MB → truncate in place
+#     containers directory missing → whole pass skipped, not an error
+#
+# Truncation is always `: > file`, never rm — see Truncate, Never Delete below.
+# Freed bytes are totalled per pass and reported in the summary.
+#
+# ==============================================================================================
 # DESIGN PRINCIPLES
 # ==============================================================================================
 #
+# Truncate, Never Delete
+#   Logs are emptied in place, never removed. The writing process keeps its open file
+#   handle and keeps logging; deleting the inode would leave a running daemon writing
+#   to a file nothing can read, and would consume more tmpfs, not less.
+#
 # Size Thresholds, Not Blind Truncation
 #   A 2MB syslog contains useful recent diagnostic history — not worth clearing.
 #   A 500MB Docker log is consuming rootfs and contains mostly noise — clear it.