chore: add script to check newest reshade release

scripts/check_reshade.sh

@@ -0,0 +1,56 @@
+#!/usr/bin/env bash
+# Check if a new ReShade version is available.
+# Usage: ./check_reshade.sh 6.6.1
+# Exit codes: 0 up-to-date, 1 update available, 2 error
+
+set -euo pipefail
+
+CURRENT="${1:-}"
+if [[ -z "$CURRENT" ]]; then
+  echo "Usage: $0 <current_version>"
+  exit 2
+fi
+
+fetch() {
+  curl -fsSL --max-time 20 "https://reshade.me/"
+}
+
+get_latest() {
+  local html
+  html="$(fetch || true)"
+  [[ -z "$html" ]] && return 1
+
+  if [[ "$html" =~ Download[[:space:]]+ReShade[[:space:]]+([0-9]+\.[0-9]+\.[0-9]+) ]]; then
+    echo "${BASH_REMATCH[1]}"
+    return 0
+  fi
+
+  return 1
+}
+
+LATEST="$(get_latest || true)"
+if [[ -z "$LATEST" ]]; then
+  echo "Could not determine latest ReShade version."
+  exit 2
+fi
+
+CMP="$(python3 - <<PY
+def norm(v):
+    p=v.split('.')
+    return list(map(int,(p+[0,0])[:3]))
+a=norm("$LATEST"); b=norm("$CURRENT")
+print((a>b)-(a<b))
+PY
+)"
+
+if [[ "$CMP" -gt 0 ]]; then
+  echo "New ReShade version available: $LATEST (you have $CURRENT)"
+  echo "Download: https://reshade.me/"
+  exit 1
+elif [[ "$CMP" -eq 0 ]]; then
+  echo "You are up-to-date: $CURRENT"
+  exit 0
+else
+  echo "Your version ($CURRENT) is newer than site ($LATEST)."
+  exit 0
+fi