Migrate Cypress (E2E) tests to Vite and TypeScript

This commit progresses the migration from Vue CLI to Vite (#230).

TypeScript migration:

- Convert JavaScript Cypress tests and configurations to TypeScript.
- Introduce `tsconfig.json` for Cypress, following official
  recommendation.

Test execution:

- Use Cypress CLI to run the tests.
- Rename Cypress commands to reflect official naming conventions.
- Start Vue server prior to Cypress execution, using
  `start-server-and-test` package based on official documentation.
- Remove dependency on Vue CLI plugin ((`@vue/cli-plugin-e2e-cypress`).

Configuration standardization (based on Cypress docs):

- Delete unused `plugins/` directory.
- Move test (spec) files to to the root directory.
- Add official ESLint plugin (`eslint-plugin-cypress`).

Changes for importing `vite.config.ts` into `cypress.config.ts`:

- Add TypeScript import assertations to files importing JSON files.
- Use ESM friendly way instead of `__dirname` to solve `ReferenceError:
  __dirname is not defined in ES module scrope`.

Other changes:

- Simplify comments in placeholder files.
- Create Cypress specific `.gitignore` for enhanced maintainability,
  clarity and scalability.
- Remove redundant `vue.config.cjs`.

package.json

@@ -13,6 +13,8 @@
     "test:unit": "vitest run --dir tests/unit",
     "test:integration": "vitest run --dir tests/integration",
     "test:e2e": "vue-cli-service test:e2e",
+    "test:cy:run": "start-server-and-test \"vite build && vite preview --port 7070\" http://localhost:7070 \"cypress run --config baseUrl=http://localhost:7070\"",
+    "test:cy:open": "start-server-and-test \"vite --port 7070 --mode production\" http://localhost:7070 \"cypress open --config baseUrl=http://localhost:7070\"",
     "lint": "npm run lint:md && npm run lint:md:consistency && npm run lint:md:relative-urls && npm run lint:eslint && npm run lint:yaml",
     "icons:build": "node scripts/logo-update.js",
     "electron:build": "vue-cli-service electron:build",
@@ -53,7 +55,6 @@
     "@typescript-eslint/parser": "^5.62.0",
     "@vitejs/plugin-legacy": "^4.1.1",
     "@vitejs/plugin-vue2": "^2.2.0",
-    "@vue/cli-plugin-e2e-cypress": "^5.0.8",
     "@vue/eslint-config-airbnb-with-typescript": "^7.0.0",
     "@vue/eslint-config-typescript": "^11.0.3",
     "@vue/test-utils": "^1.3.6",
@@ -67,6 +68,7 @@
     "electron-updater": "^6.1.4",
     "electron-vite": "^1.0.27",
     "eslint": "^8.46.0",
+    "eslint-plugin-cypress": "^2.14.0",
     "eslint-plugin-vue": "^9.6.0",
     "eslint-plugin-vuejs-accessibility": "^1.2.0",
     "icon-gen": "^3.0.1",
@@ -78,6 +80,7 @@
     "remark-preset-lint-consistent": "^5.1.2",
     "remark-validate-links": "^12.1.1",
     "sass": "^1.64.1",
+    "start-server-and-test": "^2.0.0",
     "svgexport": "^0.4.2",
     "terser": "^5.19.2",
     "tslib": "~2.4.0",