Fallback echo/log audit pass — fallback.sh, fallback_test.sh + Manual

Remove setup banners from fallback.sh and fallback_test.sh. Add Host Detection
to fallback.sh OPERATIONAL SAFEGUARDS; add Lock Acquisition + Host Detection to
fallback_test.sh. Add output tiers section to Manual-Fallback.md documenting
daemon vs one-shot output behaviour.

Fallback/fallback.sh

@@ -111,6 +111,10 @@
 #   acquire_lock() prevents two instances running simultaneously. Both would
 #   modify containers and DDNS independently — conflict is certain.
 #
+# Host Detection
+#   detect_hosts() resolves MY_ID / REMOTE_ID from master.conf at startup.
+#   Exits if the host cannot be identified — prevents running on an unknown machine.
+#
 # Silent by Default
 #   State transitions: warn() — always visible. Healthy routine cycles: log()
 #   — suppressed unless --log. Produces no output on clean cycles.
@@ -246,8 +250,6 @@ fi
 # ==============================================================================================
 # ━━━ Setup ━━━
 # ==============================================================================================
-echo ""
-echo "━━━ $ICON_GEAR Setup ━━━"
 
 if [[ "$EUID" -ne 0 ]]; then
     error "Must be run as root"