feat: security hardening suite (redaction, sanitization, yield tests, IPFS tests) - #211

You have commit messages with errors ⧗ input: feat: implement security hardening suite (Closes #149, #148, #147, #146) - #149: Add redaction formatter for Winston logger to mask Stellar secret keys, JWT tokens, *** and sensitive meta values - #148: Add sanitize-input middleware to strip XSS/injection payloads from request bodies and query params - #147: Add unit tests for pro-rata yield distribution across 2/3/10 investor splits with 0%/1%/2.5% fees - #146: Add integration tests for IPFS upload retry on 429, file size validation, and error reporting ✖ footer's lines must not be longer than 100 characters [footer-max-line-length] ✖ found 1 problems, 0 warnings ⓘ Get help: https://github.com/conventional-changelog/commitlint/#what-is-commitlint