**Title:** fix: redact PII in structured logs

[SHEROSE0]

#closes #420

Description:
This PR introduces a secure redaction layer for request body logging to ensure compliance with sensitive data handling (specifically Stellar memo PII).

Changes Implemented:

• app/lib/privacy.ts: Created a centralized utility module containing regex-based masking for emails, phone numbers, and base32 strings.
• app/lib/logger.ts: Integrated the redactPII utility into the serialization pipeline, ensuring request payloads are sanitized before logging.

Acceptance Criteria Checklist:

• PII Masked: Emails, phone numbers, and long base32 strings are masked according to requirements.
• Secure Patterns: Implementation uses a focused regex approach to avoid performance degradation.
• Clean Integration: Redaction is handled during serialization, ensuring minimal impact on log flow.
• Documentation: Added clear comments for maintainability.

Testing Notes:

• Verified redaction logic via unit-style pattern matching.
• Ensured no regression in standard log formatting.

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#closes