chore: add env consistency check script

scripts/check-env.ts

@@ -0,0 +1,108 @@
+```ts
+import fs from "node:fs";
+import path from "node:path";
+
+async function loadKeys(filePath: string): Promise<Set<string>> {
+  const raw = await fs.promises.readFile(filePath, "utf8");
+  const keys = new Set<string>();
+
+  for (const line of raw.split(/\r?\n/)) {
+    const trimmed = line.trim();
+
+    // Skip empty lines and comments
+    if (!trimmed || trimmed.startsWith("#")) {
+      continue;
+    }
+
+    const equalsIndex = trimmed.indexOf("=");
+    if (equalsIndex <= 0) {
+      continue;
+    }
+
+    const key = trimmed.slice(0, equalsIndex).trim();
+    if (key.length > 0) {
+      keys.add(key);
+    }
+  }
+
+  return keys;
+}
+
+async function main() {
+  const projectRoot = process.cwd();
+  const examplePath = path.join(projectRoot, ".env.example");
+  const envPath = path.join(projectRoot, ".env");
+
+  if (!fs.existsSync(examplePath)) {
+    console.error("Could not find .env.example at the project root.");
+    console.error("Make sure you are running this script from the repository root.");
+    process.exit(1);
+  }
+
+  const expectedKeys = await loadKeys(examplePath);
+
+  if (expectedKeys.size === 0) {
+    console.log("No keys found in .env.example (nothing to check).");
+    return;
+  }
+
+  if (!fs.existsSync(envPath)) {
+    console.log("No .env file found at the project root.");
+    console.log("Create one by copying .env.example and filling in the values.");
+    console.log("");
+    console.log("Example:");
+    console.log("  cp .env.example .env");
+    return;
+  }
+
+  const actualKeys = await loadKeys(envPath);
+
+  const missing: string[] = [];
+  const extra: string[] = [];
+
+  for (const key of expectedKeys) {
+    if (!actualKeys.has(key)) {
+      missing.push(key);
+    }
+  }
+
+  for (const key of actualKeys) {
+    if (!expectedKeys.has(key)) {
+      extra.push(key);
+    }
+  }
+
+  console.log("=== .env consistency check ===");
+  console.log(`Expected keys (from .env.example): ${expectedKeys.size}`);
+  console.log(`Actual keys   (from .env)       : ${actualKeys.size}`);
+  console.log("");
+
+  if (missing.length === 0 && extra.length === 0) {
+    console.log("✅ All keys from .env.example are present in .env, and there are no extra keys.");
+    return;
+  }
+
+  if (missing.length > 0) {
+    console.log("⚠ Missing keys in .env (present in .env.example but not in .env):");
+    for (const key of missing) {
+      console.log(`  - ${key}`);
+    }
+    console.log("");
+  }
+
+  if (extra.length > 0) {
+    console.log("ℹ Extra keys in .env (not listed in .env.example):");
+    for (const key of extra) {
+      console.log(`  - ${key}`);
+    }
+    console.log("");
+  }
+
+  console.log("If you just created your .env from .env.example,");
+  console.log("check that all required keys are present and spelled correctly.");
+}
+
+main().catch((error) => {
+  console.error("Unexpected error while checking .env:", error);
+  process.exit(1);
+});