fix: Migrate globals for node and browser even if they aren't perfect matches. (#243)

* fix: warning and error were swapped in rule severity normalization.

Fixes #241.

* chore: Update tsgolint.

* Add eslint-globals project to test the behavior of the globals field in ESLint configs.

* Replace all ts-ignore comments with ts-expect-error comments

* Fix the logic for env-matching so globals are correctly identified even with minor differences in versions.

* Fix comment.

---------

Co-authored-by: Alexander S. <sysix@sysix-coding.de>

Author: connorshea

integration_test/__snapshots__/eslint-globals.spec.ts.snap

@@ -0,0 +1,141 @@
+// Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
+
+exports[`eslint-globals > eslint-globals 1`] = `
+{
+  "config": {
+    "$schema": "./node_modules/oxlint/configuration_schema.json",
+    "categories": {
+      "correctness": "off",
+    },
+    "env": {
+      "builtin": true,
+    },
+    "overrides": [
+      {
+        "env": {
+          "browser": true,
+          "commonjs": true,
+          "es2026": true,
+          "node": true,
+          "shared-node-browser": true,
+        },
+        "files": [
+          "**/*.js",
+          "**/*.cjs",
+          "**/*.mjs",
+        ],
+        "rules": {
+          "no-unused-vars": "error",
+        },
+      },
+    ],
+    "plugins": [],
+  },
+  "warnings": [],
+}
+`;
+
+exports[`eslint-globals --js-plugins > eslint-globals--js-plugins 1`] = `
+{
+  "config": {
+    "$schema": "./node_modules/oxlint/configuration_schema.json",
+    "categories": {
+      "correctness": "off",
+    },
+    "env": {
+      "builtin": true,
+    },
+    "overrides": [
+      {
+        "env": {
+          "browser": true,
+          "commonjs": true,
+          "es2026": true,
+          "node": true,
+          "shared-node-browser": true,
+        },
+        "files": [
+          "**/*.js",
+          "**/*.cjs",
+          "**/*.mjs",
+        ],
+        "rules": {
+          "no-unused-vars": "error",
+        },
+      },
+    ],
+    "plugins": [],
+  },
+  "warnings": [],
+}
+`;
+
+exports[`eslint-globals --type-aware > eslint-globals--type-aware 1`] = `
+{
+  "config": {
+    "$schema": "./node_modules/oxlint/configuration_schema.json",
+    "categories": {
+      "correctness": "off",
+    },
+    "env": {
+      "builtin": true,
+    },
+    "overrides": [
+      {
+        "env": {
+          "browser": true,
+          "commonjs": true,
+          "es2026": true,
+          "node": true,
+          "shared-node-browser": true,
+        },
+        "files": [
+          "**/*.js",
+          "**/*.cjs",
+          "**/*.mjs",
+        ],
+        "rules": {
+          "no-unused-vars": "error",
+        },
+      },
+    ],
+    "plugins": [],
+  },
+  "warnings": [],
+}
+`;
+
+exports[`eslint-globals merge > eslint-globals--merge 1`] = `
+{
+  "config": {
+    "$schema": "./node_modules/oxlint/configuration_schema.json",
+    "categories": {
+      "correctness": "error",
+      "perf": "error",
+    },
+    "env": {
+      "builtin": true,
+    },
+    "overrides": [
+      {
+        "env": {
+          "browser": true,
+          "commonjs": true,
+          "es2026": true,
+          "node": true,
+          "shared-node-browser": true,
+        },
+        "files": [
+          "**/*.js",
+          "**/*.cjs",
+          "**/*.mjs",
+        ],
+        "rules": {
+          "no-unused-vars": "error",
+        },
+      },
+    ],
+  },
+  "warnings": [],
+}
+`;