fix(live-editing): improve generated standalone and styles handling

[dobromirts]

Closes #3935

Added missing name, version, and scripts (ng, start, build) to the generated package.json for each standalone sample — previously the file was not a valid npm package and npm start would fail in StackBlitz/CodeSandbox
Added ^ semver range prefix to exact-pinned dependency versions in sampleDependencies so samples always resolve the latest compatible version instead of being pinned to a stale exact release
DevDependencies in generated package.json are now sourced from the main package.json ranges instead of hardcoded values in shared.json, which got overwritten on every generate-live-editing run
Bumped Angular peer dependencies from ^21.0.0 to ^21.1.0 to match the installed version and ensure @angular/compiler-cli 21.1.x is resolved — required by igniteui-angular 21.1.x which uses the passThroughInput compiler API introduced in 21.1
@import "tailwindcss" is now stripped from the shared styles.scss after generate-live-editing and injected back only into samples that declare tailwindcss as a dependency — both in the live editing source viewer and in the standalone sample output from repositoryfy

Update live-editing version to 3.4.2

[Copilot]

Pull request overview

Updates the live-editing generation/repositoryfy pipeline to produce more reliable standalone samples (valid package.json + dependency ranges) and to only include Tailwind styles when a sample actually depends on Tailwind.

Changes:

• Bump gulp dev dependency to ^5.0.1.
• Post-process generated live-editing JSON to strip @import "tailwindcss" from the shared styles.scss and inject it only into samples that declare tailwindcss.
• Improve generated standalone sample package.json (add name/version/scripts, add ^ prefix for exact versions, and source devDependency ranges from the repo root package.json).

Reviewed changes

Copilot reviewed 1 out of 2 changed files in this pull request and generated 2 comments.

File	Description
package.json	Updates build tooling dependency (gulp) used by the live-editing generation tasks.
gulpfile.js	Enhances live-editing generation and repositoryfy output to conditionally manage Tailwind imports and generate a valid standalone package.json.

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