KTL-4149 feat: add TeamCity project for building landing pages

[nikpachoo]

https://youtrack.jetbrains.com/issue/KTL-4149/Publish-a-Spring-AI-with-Kotlin-tutorial-landing-page

Introduces a TeamCity DSL sub-project that builds and deploys AI-generated landing pages (exported from Lovable) to the kotlinlang S3 infrastructure.

What's included

• LandingPagesProject iterates over all configured landing pages and registers the three build configurations below for each one.
• BuildLandingPage patches vite.config.ts base path to /lp//, installs dependencies, builds with Vite, and publishes the dist/ directory.
• DeployLandingToStaging / DeployLandingToProduction sync the artifacts.