Upgrade createapp templates and specs to ESLint v10 flat config

[deepanshu44]

Hi @LoicPoullain 👋

Following up on PR #1357, this PR upgrades the foal createapp generator templates (packages/cli/templates/app/ and specs/app/) to ESLint v10 (Flat Config) and Prettier.

🌟 Summary of Changes:

• Modern Flat Config: Replaced legacy .eslintrc.js in templates/app/ and specs/app/ with native eslint.config.mjs and .prettierrc so newly generated FoalTS projects ship with ESLint v10.
• Updated Dependencies: Updated template package.json variants to use eslint v10 (^10.0.0), typescript-eslint v8 (^8.0.0), prettier (^3.0.0), and eslint-config-prettier (^10.0.0).
• CLI Service & Spec Updates: Updated @foal/cli's create-app-command.service.ts and its unit tests to copy eslint.config.mjs and .prettierrc when creating new apps.

All CLI generator unit tests are passing cleanly (295 passing). Let me know what you think.

[deepanshu44]

In order to remove the errors that were triggered by the bash E2E test file, I've tried to modify the e2e-test.sh file and make it use the local foal build instead. This makes the run pass successfully as of now.
commit: deepanshu44@3fd5635
run: CI

Previously, e2e_test.sh downloaded published @foal/* packages from the NPM registry. Those remote packages still contained older templates and failed during npm run lint. Installing the local monorepo packages (using lerna build) forced the test apps to use updated ESLint v10 (eslint.config.mjs) templates.