AutoHotkey Enter Key Remap

I want a small, tidy AutoHotkey script that changes the Enter key behavior only when I’m typing in WhatsApp Desktop or Web or Google Chat in my browser. Pressing Enter in those two apps should trigger Shift + Enter, so I get a simple line break instead of sending the message. The standard Enter action must remain untouched everywhere else on the system.

Implementation notes I expect you to cover in the code comments:
• A reliable way to detect when the active control belongs to WhatsApp Desktop, Web, or Google Chat (window title, URL check, or another solid method that works across Chrome, Edge, and Brave).
• Clean remapping of Enter → Shift + Enter within those contexts, with zero interference outside them.
• Simple turn on/off toggle (a hotkey or tray menu item is fine) so I can quickly switch the behaviour on or off.

Deliverables
1. A well-commented .ahk file with the remap logic.
2. A compiled .exe version for machines without AutoHotkey installed.
3. A quick read-me explaining where to place or run the script and how to toggle it.

If you can keep the script lightweight, readable, and free of external dependencies, that would be perfect.