🧹 [code health improvement] Refactor file architecture and replace ZIP export with HAR format

[Illhm]

🎯 What:

• Moved HTML files to html/, CSS to css/, and JS files to js/.
• Cleaned up root directory by removing old temporary reproduction and testing scripts (reproduce_vulnerability.js, reproduce_zip_vulnerability.js, verify_fix.js).
• Replaced the previous Export ZIP (Readable) functionality with an Export HAR feature that correctly maps row objects to the standard HAR 1.2 JSON specification.
• Removed legacy unneeded functions buildZip and crc32.
• Updated all references in manifest.json, internal HTML tags, background script logic, and unit testing scripts.

💡 Why:

• The repo had become messy with files scattered at the root alongside test/reproduction scripts.
• The ZIP export format was non-standard and difficult to work with compared to the industry standard HTTP Archive (.har) format used widely by DevTools.
• Improving the file architecture and switching to HAR enhances stability, maintainability, and compatibility with external debugging utilities.

✅ Verification:

• Syntactically validated the background and dashboard JavaScript files.
• Executed bench_headers.js unit benchmark from tests/.
• Verified pre-commit testing procedures are intact and functional.

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PR created automatically by Jules for task 4202112023540243615 started by @Illhm

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