Updated `PROJECT_STATUS.md` with completed modules (`auth`, `groups`, `tags`) and unit testing progress, including marked tests for controllers and services as done. Added logical and conceptual database models (`DATABASE_SCHEMA_PLAN.md`) and revised implementation statuses in `IMPLEMENTATION_GUIDE.md`.
Added detailed documentation files, including project overview, current status, specifications, implementation guide, and README structure. Organized content to improve navigation and streamline project understanding.
