🛡️ Sentinel: [CRITICAL] Fix PII leak in Sentry attribution

[google-labs-jules]

🚨 Severity: CRITICAL
💡 Vulnerability: User email added to SentrySDK leaked into global scope on throw.
🎯 Impact: Subsequent events would wrongly contain this PII.
🔧 Fix: Used defer to clear user upon block exit.
✅ Verification: Code review confirms cleanup via defer.

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PR created automatically by Jules for task 139653031811761464 started by @TytaniumDev

[google-labs-jules]

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