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>

eslint/use-exact-imports.js

@@ -3,20 +3,29 @@ const BANNED_IMPORTS = [
   '@fortawesome/free-solid-svg-icons',
 ]
 
-exports.create = function create(context) {
-  return {
-    ImportDeclaration(node) {
-      const source = node.source
-      if (typeof source.value !== 'string') {
-        return
-      }
-      if (BANNED_IMPORTS.includes(source.value)) {
-        context.report({
-          node,
-          message:
-            'Import the specific thing you want instead of the entire package',
-        })
-      }
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'Prevent importing entire icon packages',
     },
-  }
+    schema: [],
+  },
+  create(context) {
+    return {
+      ImportDeclaration(node) {
+        const source = node.source
+        if (typeof source.value !== 'string') {
+          return
+        }
+        if (BANNED_IMPORTS.includes(source.value)) {
+          context.report({
+            node,
+            message:
+              'Import the specific thing you want instead of the entire package',
+          })
+        }
+      },
+    }
+  },
 }