fix: add PIL MAX_IMAGE_PIXELS=50M and explicit >10000px rejection (audit #6)

fix: add extension_valid key to validate_file() — was always True (audit #1)

feat(quality): add image quality gate before forensic analysis

fix: audit pass — unused imports, None crash guard, emojis, accuracy claims, broken f-strings

Optimize file validation order for DoS protection

Add file validation utility (#4)

Initial commit: Project structure and documentation