Fix Gen 1/2 battle, menu, PC and audio parity gaps; wire luacheck into CI

CLOSES #1484, CLOSES #1486, CLOSES #1513, CLOSES #1517, CLOSES #1556, CLOSES #1564, CLOSES #1567

scripts/lint.sh

@@ -7,7 +7,8 @@
 # the nil global), unused values, unreachable code. The .luacheckrc mutes the
 # cosmetic categories the codebase lives with, so what prints is worth a look.
 #
-#   scripts/lint.sh            lint src/
+#   scripts/lint.sh            full advisory report over every shipped tree
+#   scripts/lint.sh --gate     only the codes CI blocks on (0xx, 1xx, 511)
 #   scripts/lint.sh src tools  lint specific paths
 #
 # Install once with:  luarocks install luacheck
@@ -15,9 +16,27 @@
 set -uo pipefail
 cd "$(dirname "$0")/.."
 
+DEFAULT_PATHS=(main.lua conf.lua src data/scripts mods tools)
+
+GATE=0
+if [ "${1:-}" = "--gate" ]; then
+  GATE=1
+  shift
+fi
+
 if ! command -v luacheck >/dev/null 2>&1; then
   echo "luacheck not found on PATH (install: luarocks install luacheck)" >&2
   exit 2
 fi
 
-luacheck "${@:-src}"
+if [ "$#" -gt 0 ]; then
+  PATHS=("$@")
+else
+  PATHS=("${DEFAULT_PATHS[@]}")
+fi
+
+if [ "$GATE" = "1" ]; then
+  exec luacheck "${PATHS[@]}" -q --codes --only 0 1 511
+fi
+
+luacheck "${PATHS[@]}"