feat: move .eslintignore into .eslintrc.cjs ignorePatterns (#1262)

## PR Checklist

- [x] Addresses an existing open issue: fixes #1261
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/create-typescript-app/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/create-typescript-app/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Removes the `.eslintignore` file and its templating. Instead adds the
`ignorePatterns` entry in `.eslintrc.cjs` and its templates.

Also adds `.eslintignore` to the list of cleared unnecessary files.

Author: JoshuaKGoldberg

.eslintignore

@@ -22,6 +22,7 @@ module.exports = {
 		"plugin:regexp/recommended",
 		"plugin:vitest/recommended",
 	],
+	ignorePatterns: ["!.*", "coverage*", "lib", "node_modules", "pnpm-lock.yaml"],
 	overrides: [
 		{
 			extends: ["plugin:markdown/recommended"],

.eslintrc.cjs

@@ -6,7 +6,7 @@ jobs:
       - uses: ./.github/actions/prepare
       - run: pnpm run build
       - run: pnpm run test:initialize
-      # The template's .eslintignore only ignores coverage, not coverage-*
+      # The template's ESLint ignorePatterns only ignores coverage, not coverage-*
       # https://github.com/JoshuaKGoldberg/create-typescript-app/issues/1131
       - if: always()
         run: mv coverage coverage-initialize

.github/workflows/test-initialize.yml

@@ -6,7 +6,7 @@ jobs:
       - uses: ./.github/actions/prepare
       - run: pnpm run build
       - run: pnpm run test:migrate
-      # The template's .eslintignore only ignores coverage, not coverage-*
+      # The template's ESLint ignorePatterns only ignores coverage, not coverage-*
       # https://github.com/JoshuaKGoldberg/create-typescript-app/issues/1131
       - if: always()
         run: mv coverage coverage-migrate

.github/workflows/test-migrate.yml

@@ -1,17 +1,5 @@
 // Vitest Snapshot v1, https://vitest.dev/guide/snapshot.html
 
-exports[`expected file changes > .eslintignore 1`] = `
-"--- a/.eslintignore
-+++ b/.eslintignore
-@@ ... @@
- !.*
--coverage*
-+coverage
- lib
- node_modules
- pnpm-lock.yaml"
-`;
-
 exports[`expected file changes > .eslintrc.cjs 1`] = `
 "--- a/.eslintrc.cjs
 +++ b/.eslintrc.cjs
@@ -29,6 +17,15 @@ exports[`expected file changes > .eslintrc.cjs 1`] = `
  /** @type {import("@types/eslint").Linter.Config} */
  module.exports = {
  	env: {
+@@ ... @@ module.exports = {
+ 		"plugin:regexp/recommended",
+ 		"plugin:vitest/recommended",
+ 	],
+-	ignorePatterns: ["!.*", "coverage*", "lib", "node_modules", "pnpm-lock.yaml"],
++	ignorePatterns: ["!.*", "coverage", "lib", "node_modules", "pnpm-lock.yaml"],
+ 	overrides: [
+ 		{
+ 			extends: ["plugin:markdown/recommended"],
 @@ ... @@ module.exports = {
  			rules: {
  				// These off-by-default rules work well for this repo and we like them on.

script/__snapshots__/migrate-test-e2e.js.snap

@@ -9,7 +9,6 @@ import packageData from "../package.json" assert { type: "json" };
 const filesExpectedToBeChanged = [
 	"README.md",
 	"knip.json",
-	".eslintignore",
 	".eslintrc.cjs",
 	".github/workflows/test.yml",
 	".gitignore",

script/migrate-test-e2e.js

@@ -12,6 +12,7 @@ const globPaths = [
 	".github/codecov.yml",
 	".babelrc",
 	".npmignore",
+	".eslintignore",
 	".eslintrc",
 	"CODE_OF_CONDUCT.md",
 	"CONTRIBUTING.md",

src/steps/clearUnnecessaryFiles.ts

@@ -58,6 +58,7 @@ describe("createESLintRC", () => {
 				    node: true,
 				  },
 				  extends: ["eslint:recommended", "plugin:n/recommended"],
+				  ignorePatterns: ["!.*", "lib", "node_modules", "pnpm-lock.yaml"],
 				  overrides: [
 				    {
 				      extends: ["plugin:@typescript-eslint/recommended"],
@@ -124,6 +125,7 @@ describe("createESLintRC", () => {
 				    "plugin:regexp/recommended",
 				    "plugin:vitest/recommended",
 				  ],
+				  ignorePatterns: ["!.*", "coverage", "lib", "node_modules", "pnpm-lock.yaml"],
 				  overrides: [
 				    {
 				      extends: ["plugin:markdown/recommended"],

src/steps/writing/creation/createDotESLintignore.test.ts

@@ -24,6 +24,12 @@ module.exports = {
 			options.excludeTests ? "" : `"plugin:vitest/recommended",`
 		}
 	],
+	ignorePatterns: [
+		"!.*",${options.excludeTests ? "" : `\n		"coverage",`}
+		"lib",
+		"node_modules",
+		"pnpm-lock.yaml",
+	],
 	overrides: [${
 		options.excludeLintMd
 			? ""

src/steps/writing/creation/createDotESLintignore.ts

@@ -1,5 +1,4 @@
 import { Options } from "../../../shared/types.js";
-import { createDotESLintignore } from "./createDotESLintignore.js";
 import { createDotGitignore } from "./createDotGitignore.js";
 import { createESLintRC } from "./createESLintRC.js";
 import { createTsupConfig } from "./createTsupConfig.js";
@@ -11,7 +10,6 @@ import { writePackageJson } from "./writePackageJson.js";
 export async function createRootFiles(options: Options) {
 	return {
 		".all-contributorsrc": await writeAllContributorsRC(options),
-		".eslintignore": createDotESLintignore(options),
 		".eslintrc.cjs": await createESLintRC(options),
 		".gitignore": createDotGitignore(options),
 		...(!options.excludeLintMd && {