fix(vue-js): modernize deps, require Node ≥20, fix HMR and JSON import

[MelentQ]

Changes in the Vue.js template

• Updated minimum Node.js version in engines from >=14.18.0 to >=20.19.6 to match Vite 7 requirements (Vite 7 dropped support for Node 18 and earlier).
• Updated all dependencies and devDependencies to their latest versions as of December 2025.
• Replaced deprecated assert with with for JSON import syntax (assert { type: 'json' } → with { type: 'json' }) to ensure compatibility with current Node.js/ESM standards.
• Added explicit server configuration in vite.config.js to fix HMR issues when developing the extension:

server: {
  port: 5173,
  strictPort: true,
  hmr: {
    host: 'localhost',
    port: 5173,
  },
},