fix(react-template): remove demo tests and format generated files after remove:demo

[pplancq]

Closes #1850

Bug description

After running npm run remove:demo in a freshly initialized @pplancq/react-template project, the validation pipeline failed because:

1. Orphaned demo tests in tests/unit/demo/ still imported removed @Demo/... modules.
2. Generated source files used single quotes and arrow-function styles that conflicted with the project's Prettier/ESLint rules.
3. package.json and tsconfig.json were rewritten without a trailing newline, causing Prettier to complain.
4. The demo e2e test in tests/e2e/demo.test.ts was left behind, failing against the new home page.

Changes

• Remove tests/unit/demo/ and tests/e2e/demo.test.ts during remove:demo.
• Add a minimal tests/e2e/home.test.ts so the e2e suite still has tests to run.
• Rewrite all generated .ts/.tsx files with double quotes and Prettier-compatible formatting.
• Use () => { ... } for the empty ContainerModule callback to avoid the @typescript-eslint/no-unused-vars error.
• Use implicit return in the generated Home component to satisfy arrow-body-style.
• Add trailing newlines to rewritten package.json and tsconfig.json, then run Prettier on them to ensure they match the project's formatting rules.

Verification

Tested by copying the template to a temporary directory, running node scripts/removeDemo.cjs, and executing the full validation command from the issue:

npm run lint && npm run test -- --coverage && npm run build

All steps now pass.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud