reuse files when generate report within hardlinks(#545)

[todti]

reduces disk usage and I/O when generating multiple reports into the same output directory by reusing identical files via hardlinks instead of writing duplicates.

• Adds content-hash based deduplication in FileSystemReportFiles with atomic tmp+rename and a safe fallback to regular writes when hardlinking isn’t possible.
• Adds unit tests and an e2e check ensuring shared static assets and attachments remain accessible across multiple awesome reports (inode check on non-Windows).

refer to #545 #486

[github-actions]

Allure Report Summary

	Name	Duration	Stats	New	Flaky	Retry	Report
	Allure 3 Report	26m 19s	6119    15    12	21	0	0
	My Dashboard	26m 19s	6119    15    12	21	0	0	View
	Allure 3 GitHub actions run (2026-04-15T16:13:23.253Z)	26m 19s	6119    15    12	21	0	0	View

[jrett2]

FYI this is a duplicate of #486