🛡️ Sentinel: [CRITICAL] Fix command injection in PowerShell TTS

[omsingh02]

🚨 Severity: CRITICAL
💡 Vulnerability: Direct string interpolation of an untrusted text argument into a PowerShell script executed via subprocess.Popen in FeedbackManager.speak_text(). An attacker could break out of the string wrapper (using quotes and semicolons) to achieve arbitrary command execution on Windows.
🎯 Impact: Malicious input passed to the TTS engine could compromise the host machine with the privileges of the running application.
🔧 Fix: Changed the input passing mechanism. Python now Base64 encodes the TTS text payload, safely passes only the Base64 string to PowerShell, and PowerShell natively decodes it back to UTF-8 before passing it to the SpeechSynthesizer. This removes any string interpolation risks.
✅ Verification: Verified by ensuring the code behaves safely even if the text includes characters like " or ; because the string is transported safely as base64. Also ensured Python syntax passes compilation and the test suite passes smoothly. Added entry to .jules/sentinel.md journal.

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PR created automatically by Jules for task 6490587686477468003 started by @omsingh02

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