- Merge lang package into constants (add IsValidLang, ValidateLang, AllLangs)
- Rename internal/services to internal/email for consistency with pdf package
- Rename types to avoid redundancy: EmailService→Service, EmailConfig→Config
- Update all imports and references across codebase
- Delete internal/lang directory (functions moved to constants)
- Update all imports from 'constants' to 'c' for brevity
- Replace all 'constants.' references with 'c.'
- Fix remaining hardcoded content-type headers in httputil
- Fix remaining hardcoded User-Agent and Accept headers
- Rename CSRF receiver from 'c' to 'csrf' to avoid conflict
- Add ContentTypePlainSimple constant for Accept header matching
- Fix JSONCached to use proper integer formatting
- Create internal/constants package with all hardcoded values
(environment, cookies, themes, headers, routes, cache)
- Create internal/httputil package for HTTP helper functions
- Update all handlers and middleware to use centralized constants
- Reorganize documentation with numbered prefixes (00-26)
- Remove duplicate docs from validation folder and docs/
- Delete handlers/constants.go (moved to internal/constants)
juanatsap