feat: Integrate dynamic API key injection

[willum070]

🔑 feat: Enable Dynamic API Key Injection & Restore Playwright Tests

This PR accomplishes the following:

• API Key Placeholders: Replaces hardcoded API keys with a placeholder ("GOOGLE_MAPS_API_KEY") in all sample files where API keys are defined.
• Dynamic Vite Injection: Updates vite.config.js with a new pre-enforced code-transform plugin. During local builds, this works alongside the existing html-transform plugin to scan JS/TS/HTML code for the "GOOGLE_MAPS_API_KEY" placeholder and dynamically injects the API key loaded from the local .env file or CI environment.
• Test Environment Keys (JS_MAPS_DEV_KEY): Pipes the repository's dedicated development key (${{ secrets.JS_MAPS_DEV_KEY }}) into the CI runner during automated tests (tests.yml). This ensures the vite.config.js plugins correctly inject the dev key during test builds.
• Production Environment Keys (JS_MAPS_PROD_KEY): Pipes the repository's production API key (${{ secrets.JS_MAPS_PROD_KEY }}) into the global environment block of the release.yml workflow. This ensures the Vite plugins inject the production key into the final dist/ HTML and JS artifacts when building public samples for the documentation.
• Restores & Fixes Playwright Tests: Re-enables the Playwright End-to-End test suite (e2e/samples.spec.ts). Resolves a critical bug where vite preview was spawning background zombie processes and causing GitHub Actions to hang indefinitely by rewriting the test runner to execute the underlying vite/bin/vite.js Node script directly.

These changes provide the following benefits:

• Decoupling the API key from source code makes it much easier to update and greatly improves security.
• The API key placeholder means that our raw sample code no longer exposes an actual API key, helping prevent casual abuse.
• We now strictly separate our API key usage: contributors use their own local key, automated tests use JS_MAPS_DEV_KEY, and public releases use JS_MAPS_PROD_KEY. Since our production API key no longer has local port restrictions, this isolation greatly enhances security and prepares us to make life much more difficult for scrapers.