Update Electron and better-sqlite3 dependencies to version 40.6.1; adjust Node.js engine requirement to 24.14.0 in package.json and .nvmrc

scripts/rebuild-nodecg-native.mjs

@@ -23,7 +23,7 @@ function run(command, args, cwd) {
       env: {
         ...process.env,
         npm_config_runtime: "electron",
-        npm_config_target: "39.5.1",
+        npm_config_target: "40.6.1",
         npm_config_disturl: "https://electronjs.org/headers",
       },
     });
@@ -48,7 +48,7 @@ for (const dir of moduleDirs) {
   console.log(`\n[rebuild-native] Rebuilding better-sqlite3 in: ${dir}`);
   await run(
     "npm",
-    ["rebuild", "better-sqlite3", "--runtime=electron", "--target=39.5.1", "--dist-url=https://electronjs.org/headers"],
+    ["rebuild", "better-sqlite3", "--runtime=electron", "--target=40.6.1", "--dist-url=https://electronjs.org/headers"],
     dir,
   );
 }