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>

src/view/com/testing/TestCtrls.e2e.tsx

@@ -1,9 +1,9 @@
 import {useState} from 'react'
-import {LogBox, Pressable, View, TextInput} from 'react-native'
+import {LogBox, Pressable, TextInput, View} from 'react-native'
 import {useQueryClient} from '@tanstack/react-query'
 
 import {BLUESKY_PROXY_HEADER} from '#/lib/constants'
-import {useSessionApi, useAgent} from '#/state/session'
+import {useAgent, useSessionApi} from '#/state/session'
 import {useLoggedOutViewControls} from '#/state/shell/logged-out'
 import {useOnboardingDispatch} from '#/state/shell/onboarding'
 import {navigate} from '../../../Navigation'
@@ -50,6 +50,8 @@ export function TestCtrls() {
   return (
     <View style={{position: 'absolute', top: 100, right: 0, zIndex: 100}}>
       <TextInput
+        accessibilityLabel="Text input field"
+        accessibilityHint="Enter proxy header"
         testID="e2eProxyHeaderInput"
         onChangeText={val => setProxyHeader(val as any)}
         onSubmitEditing={() => {