Docs: Core Concepts of Interactivity API - "Declarative vs. Imperative approaches" page

[WPLake]

We suggest including a "Declarative vs. Imperative Approaches" page in the Core Concepts section for the iAPI.

The page should showcase a visual example highlighting the drawbacks of the imperative approach and promoting the declarative one. This is necessary because WordPress has historically been heavily related to PHP, and many experienced, old-school WP developers may not have any reactive background at all.

The outline can be:

1. Introduction - Terms description
2. Drawbacks of the Imperative approach
3. Benefits of the Declarative approach
4. Declarative iAPI Playground example

We already have a similar chapter in our WPLake blog article, so it can be used as a base and amended to match the wp.org writing style guides.