fix: rename parameters for slowapi compatibility

feat: update rate limit to 1/2s, custom error message, and SEO PNG placeholder

feat: unified build for Hugging Face Spaces

Brand: Rebrand project to Redac (MVP status).

UI/UX: Restore dynamic score colors and refine loading animations.

Final: Stabilize PII engine with 100% verified test coverage.

UI/Core: Add large document examples and silence MISC warnings.

Build: Stabilize PII engine with professional test suite and persistent model volumes.

Initial commit: Privacy Gateway with Multi-language PII detection (EN/FR) and Docker support