fix(Crunchyroll): restore iframe playback detection

[CreepsoOff]

Description

Crunchyroll uses two different video player implementations. PR #10587 removed iframe support in favor of direct
<video> element detection, but this caused the presence to remain stuck on "Browsing..." on /watch/ pages for
users with the iframe-based player (https://static.crunchyroll.com/vilos-v2/web/vilos/player.html).

This PR re-introduces iframe support to ensure compatibility with both player types:

1. Direct video player: Checks for <video> in #player-container or document root
2. Iframe player (vilos): Receives playback data from iframe via iFrameData event

Changes

• metadata.json: Re-enable iframe injection with "iframe": true and "iFrameRegExp": "static.crunchyroll.com"
• iframe.ts (new): Polls for <video> element inside the player iframe and sends playback data via
  iframe.send()
• presence.ts: Add iFrameData event handler + dual playback detection (direct video with iframe fallback)

All existing features (privacy mode, hideWhenPaused, timestamps, buttons, browsing pages) remain unchanged.

Acknowledgements

• I read the Activity Guidelines
• I linted the code by running npm run lint
• The PR title follows the repo's commit conventions

Screenshots

Proof showing the creation/modification is working as expected

[theusaf]

Use iframe UpdateData event