feat: stream private office screens

deploy/coturn/tera-coturn-preflight

@@ -0,0 +1,29 @@
+#!/bin/sh
+# Fail a coturn start before an example placeholder becomes a public credential.
+set -eu
+
+config=${TURN_CONFIG:-/etc/turnserver.conf}
+
+test -r "$config" || { echo "coturn preflight: cannot read $config" >&2; exit 1; }
+if grep -q 'REQUIRED_' "$config"; then
+  echo "coturn preflight: unresolved REQUIRED_ placeholder in $config" >&2
+  exit 1
+fi
+
+secret=$(sed -n 's/^static-auth-secret=//p' "$config")
+case "$secret" in
+  *[!0-9A-Fa-f]*|'')
+    echo "coturn preflight: static-auth-secret must be hexadecimal" >&2
+    exit 1
+    ;;
+esac
+test "${#secret}" -ge 64 || {
+  echo "coturn preflight: static-auth-secret must contain at least 64 hex characters" >&2
+  exit 1
+}
+
+for path in /etc/coturn/certs/turn.fullchain.pem /etc/coturn/certs/turn.privkey.pem; do
+  test -r "$path" || { echo "coturn preflight: cannot read $path" >&2; exit 1; }
+done
+
+exit 0