Upgrade ESLint to v9 with flat config (#9680)

* Upgrade ESLint to v9 with flat config

- Upgrade eslint from v8 to v9.18.0
- Migrate from .eslintrc.js to eslint.config.mjs (flat config)
- Upgrade typescript-eslint to v8.20.0 (unified package)
- Replace eslint-plugin-import with eslint-plugin-import-x for flat config support
- Add globals package for environment globals
- Update eslint-plugin-bsky-internal with proper meta objects for ESLint v9
- Fix deprecated context.getScope() API usage
- Update bskyembed to use flat config
- Remove deprecated --ext flag from lint scripts
- Configure rules to maintain previous behavior while using new ESLint version

* Fix varsIgnorePattern to require character after underscore

Restore the original pattern `^_.+` instead of `^_` so that lingui's
`const { _ } = useLingui()` will still be flagged when unused.

* Update ESLint rule tests for flat config format

- Update RuleTester to use flat config languageOptions instead of
  eslintrc parser format
- Remove duplicate test case that ESLint v9 now detects
- Add Jest globals for test files

* update eslint package versions

* lint android a11y

* enable typechecked rules, switch them to warn

* fix yarn lock ci

* Fix CI failure

* Remove unused globals?

* Organize a bit, add quiet to main lint command

* Allow ternary

---------

Co-authored-by: Claude <noreply@anthropic.com>
Co-authored-by: Eric Bailey <git@esb.lol>

package.json

@@ -41,7 +41,7 @@
     "test-watch": "NODE_ENV=test jest --watchAll",
     "test-ci": "NODE_ENV=test jest --ci --forceExit --reporters=default --reporters=jest-junit",
     "test-coverage": "NODE_ENV=test jest --coverage",
-    "lint": "eslint --cache --ext .js,.jsx,.ts,.tsx src",
+    "lint": "eslint --cache --quiet src",
     "lint-native": "swiftlint ./modules && ktlint ./modules",
     "lint-native:fix": "swiftlint --fix ./modules && ktlint --format ./modules",
     "typecheck": "tsc --project ./tsconfig.check.json",
@@ -231,6 +231,7 @@
     "@babel/core": "^7.26.0",
     "@babel/preset-env": "^7.26.0",
     "@babel/runtime": "^7.26.0",
+    "@eslint/js": "^9.39.2",
     "@expo/config-plugins": "~54.0.1",
     "@lingui/cli": "^4.14.1",
     "@lingui/macro": "^4.14.1",
@@ -248,23 +249,24 @@
     "@types/psl": "^1.1.1",
     "@types/react": "^19.1.12",
     "@types/react-dom": "^19.1.9",
-    "@typescript-eslint/eslint-plugin": "^7.18.0",
-    "@typescript-eslint/parser": "^7.18.0",
     "babel-jest": "^29.7.0",
     "babel-plugin-macros": "^3.1.0",
     "babel-plugin-module-resolver": "^5.0.2",
     "babel-plugin-react-compiler": "^19.1.0-rc.3",
     "babel-preset-expo": "~54.0.0",
-    "eslint": "^8.19.0",
+    "eslint": "^9.39.2",
+    "eslint-import-resolver-typescript": "^4.4.4",
     "eslint-plugin-bsky-internal": "link:./eslint",
-    "eslint-plugin-ft-flow": "^2.0.3",
-    "eslint-plugin-import": "^2.31.0",
-    "eslint-plugin-lingui": "^0.2.0",
-    "eslint-plugin-react": "^7.33.2",
+    "eslint-plugin-import-x": "^4.16.1",
+    "eslint-plugin-lingui": "^0.11.0",
+    "eslint-plugin-react": "^7.37.5",
     "eslint-plugin-react-compiler": "^19.1.0-rc.2",
-    "eslint-plugin-react-native-a11y": "^3.3.0",
-    "eslint-plugin-simple-import-sort": "^12.0.0",
+    "eslint-plugin-react-hooks": "^7.0.1",
+    "eslint-plugin-react-native": "^5.0.0",
+    "eslint-plugin-react-native-a11y": "^3.5.1",
+    "eslint-plugin-simple-import-sort": "^12.1.1",
     "file-loader": "6.2.0",
+    "globals": "^17.0.0",
     "husky": "^8.0.3",
     "is-ci": "^3.0.1",
     "jest": "^29.7.0",
@@ -279,6 +281,7 @@
     "ts-node": "^10.9.1",
     "ts-plugin-sort-import-suggestions": "^1.0.4",
     "typescript": "^5.9.2",
+    "typescript-eslint": "^8.53.0",
     "webpack-bundle-analyzer": "^4.10.1"
   },
   "resolutions": {
@@ -288,7 +291,6 @@
     "**/@react-native-async-storage/async-storage": "2.2.0",
     "**/expo-constants": "18.0.8",
     "**/expo-device": "7.1.4",
-    "**/zod": "3.23.8",
     "**/multiformats": "9.9.0",
     "unicode-segmenter": "0.14.5"
   },