meta: add a eslint config that can find unused variables in our typescript

src/js/eslint.config.mjs

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+import globals from "globals";
+import tseslint from "typescript-eslint";
+
+export default [
+  { files: ["internal/**/*.ts"] },
+  { files: ["node/**/*.ts"] },
+  { ignores: ["thirdparty"] },
+  { languageOptions: { globals: globals.browser } },
+  { languageOptions: { parser: tseslint.parser } },
+  { rules: { "no-unused-vars": "error" } },
+];

src/js/eslint.fmt.mjs

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+export default function (results) {
+  const sgr = c => "\x1b" + "[" + c + "m";
+  const reset = sgr(0);
+  const gray = s => sgr(2) + s + reset;
+  const green = s => sgr(32) + s + reset;
+  const cyan = s => sgr(36) + s + reset;
+
+  for (const item of results) {
+    if (item.messages.length === 0) {
+      continue;
+    }
+    for (const jtem of item.messages) {
+      console.log(
+        `.${item.filePath.substring(process.cwd().length)}:${green(jtem.line)}:${cyan(jtem.column)}: ${gray(jtem.ruleId)} ${jtem.message}`,
+      );
+    }
+  }
+}

src/js/package.json

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+{
+  "scripts": {
+    "lint": "bun run eslint --format ./eslint.fmt.mjs"
+  },
+  "dependencies": {
+    "typescript-eslint": "^8.8.0"
+  }
+}