Improve security and robustness of x-frame-bypass component

[niutech]

Analyzed the repository and identified critical security vulnerabilities (cross-origin leakage) and functional bugs (broken navigation on deep clicks, failed injection on headless HTML).

Implemented a comprehensive set of fixes:

1. Security: Removed 'allow-same-origin' from the default sandbox. This ensures that even if a malicious site is bypassed and embedded, it cannot access the parent page's data.
2. Communication: Migrated to 'postMessage' for requesting new loads, which works even in a strict sandbox.
3. Robustness: Improved event listeners to correctly handle clicks on child elements of links and improved the injection logic to handle HTML documents that lack a tag.
4. Features: Added local URL support for easier development and a configurable 'proxies' attribute.

Verified the fixes with a Playwright test suite reproducing all identified issues.

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PR created automatically by Jules for task 18412575885757803260 started by @niutech

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