Feature Request: Native support for managing and injecting custom HTTP Request Headers (to bypass CloudFront WAF/Auth on Staging)

Description

Currently, there is no native, out-of-the-box way to inject custom HTTP Request Headers (such as Authorization: Bearer ... or custom security bypass flags like x-mtb-control: value) globally across all simulated device viewports.

When testing websites in staging, preprod, or local environments protected by CloudFront WAF or AWS Shield, specific headers are strictly required to grant access. Without a native way to inject these headers, every single viewport simultaneously triggers a 403 Forbidden (The request could not be satisfied) error generated by CloudFront, completely blocking the ability to do multi-device responsive testing.

Here is an example of what happens when trying to test a protected staging URL without the ability to inject the required security header:

✨ Describe the solution you'd like

It would be amazing to have a native "Request Headers" manager inside Responsively App.

• A simple UI (global or per-tab) where users can add key-value pairs for custom headers.
• Once active, these headers should be automatically appended to every request made by all active device viewports simultaneously, preventing CloudFront/WAF blocks.

Describe alternatives you've considered

• Browser Extensions: While Responsively supports extensions (like ModHeader), managing them inside the app can sometimes be clunky, inconsistent across updates, or fail to apply across all viewports correctly.
• Proxy Tools: Using Charles Proxy or Fiddler works, but it requires configuring external software, which complicates the workflow for a quick responsive check.
• URL Query Parameters: Modifying backend code to accept headers via query params (e.g., ?myheader=val) is a workaround, but it compromises security and isn't ideal for production-ready environments.