Request a stable screenshot API that captures the current rendered frame without waiting for page stability

@dgozman is already working on this.

Since Aug 24, 2026.

## Summary

I'd like to request a more stable screenshot API in `playwright-cli`.

Today, `playwright-cli screenshot` can fail on complex pages because of things like font readiness, pending resource loading, or unstable rendering state.

I also tried bypassing it with `run-code` + CDP `Page.captureScreenshot`, but that is still not reliable enough on some real pages.

## What I need

I need a screenshot API with this behavior:

- do not wait for page stability
- do not wait for fonts or all resources to finish loading
- just capture whatever is currently rendered in the browser right now
- if the page is partially rendered, that is fine
- if resources are still loading, that is also fine
- returning a valid screenshot is more important than waiting for a "perfect" screenshot

## Why this matters

For debugging and E2E evidence collection, an imperfect screenshot is often much better than no screenshot.

Right now, there is no reliable "capture now" API:
- the built-in screenshot path can fail
- direct `run-code` + CDP is also not stable enough as a workaround

## Request

Could `playwright-cli` provide a stable screenshot API or mode whose contract is:

> capture the current rendered browser frame as-is, without waiting for page stability, font readiness, or resource completion

Something like:
- `playwright-cli screenshot --capture-now`
- `playwright-cli screenshot --no-wait`
- `playwright-cli screenshot --best-effort`

The exact name is not important. The key is to prioritize **operational reliability** over screenshot completeness.