feat(docs): Pay-per-event with usage not included disclaimer (#2229)

Resolves: apify/apify-core#24692

Adds PPE+U to docs
Swap screenshot for current version in console


Preview for this PR was built for commit
[`4eeac644`](4eeac64)
and is ready at https://pr-2229.preview.docs.apify.com

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Documentation-only edits (wording and screenshots) with no runtime or
API behavior changes.
> 
> **Overview**
> Updates the Store pricing-model docs to clarify **Pay per event**
semantics, explicitly calling out that some Actors may bill platform
usage separately and adding a caution block plus an example screenshot.
> 
> Reorders/replaces screenshots in the **Rental** and **Pay per event**
sections to match the current Console/Store UI and adjusts related
wording/headings for clarity.
> 
> <sup>Written by [Cursor
Bugbot](https://cursor.com/dashboard?tab=bugbot) for commit
2bf7b28. Configure
[here](https://cursor.com/dashboard?tab=bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

Author: stetizu1