Fix Unexpected Keyword in MediaManager and Add Build Linting

- Fix corrupted line in src/MediaManager.html causing syntax error.
- Add ESLint integration to build process to prevent future syntax errors.
- Create .eslintrc.js with TypeScript and HTML support.
- Relax strict lint rules to accommodate existing codebase.

.eslintrc.js

@@ -0,0 +1,57 @@
+module.exports = {
+  env: {
+    browser: true,
+    es2021: true,
+    node: true,
+  },
+  extends: [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/recommended",
+  ],
+  parser: "@typescript-eslint/parser",
+  parserOptions: {
+    ecmaVersion: "latest",
+    sourceType: "module",
+  },
+  plugins: [
+    "@typescript-eslint",
+    "html",
+  ],
+  globals: {
+    "google": "readonly",
+    "Logger": "readonly",
+    "item": "writable",
+    "Utilities": "readonly",
+    "state": "writable",
+    "ui": "writable",
+    "controller": "writable",
+    "gapi": "readonly",
+  },
+  rules: {
+    "@typescript-eslint/no-explicit-any": "off",
+    "@typescript-eslint/no-unused-vars": "off", // Too noisy for existing codebase
+    "no-unused-vars": "off",
+    "prefer-const": "off",
+    "no-var": "off",
+    "no-undef": "off",
+    "no-redeclare": "off",
+    "no-empty": "warn",
+    "@typescript-eslint/ban-types": "off",
+    "@typescript-eslint/no-empty-function": "off",
+    "@typescript-eslint/no-var-requires": "off",
+    "no-useless-escape": "off",
+    "no-extra-semi": "off",
+    "no-array-constructor": "off",
+    "@typescript-eslint/no-array-constructor": "off",
+    "@typescript-eslint/no-this-alias": "off",
+    "@typescript-eslint/ban-ts-comment": "off",
+    "no-prototype-builtins": "off"
+  },
+  overrides: [
+    {
+      files: ["*.html"],
+      parser: "espree", // Use default parser for HTML scripts if TS parser fails, or just rely on plugin handling
+      // Actually plugin-html handles it. But we usually need to specify not to use TS rules that require type info if we don't have full project info for snippets.
+    }
+  ]
+};