🛡️ Sentinel: [HIGH] Fix XSS vulnerability in HTML report generation

[tejasbhor]

🛡️ Sentinel: [HIGH] Fix XSS vulnerability in HTML report generation

Severity: HIGH
Vulnerability: Cross-Site Scripting (XSS) vulnerability was present in the report_service.py where manual string interpolations built the HTML report, leaving dynamic and user-provided properties like job_id and data_source unsanitized.
Impact: An attacker could inject malicious JavaScript or HTML directly into the rendered report via user-controlled IDs and data source strings, potentially leading to session hijacking, malicious redirects, or defacement when viewing the report in a browser.
Fix: Added python's html.escape() to all dynamic string variables before rendering them in the manual f-string. To avoid an UnboundLocalError, the local html variable was renamed to html_content. Finally, ensured string slicing properly occurs before string escaping.
Verification: Verified against a custom test (test_xss.py) which ensures script and img tags are properly encoded and no longer vulnerable. Checked via ruff to ensure zero linting issues.

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PR created automatically by Jules for task 14836851874452981505 started by @tejasbhor

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