docs: implement professional documentation structure and project hygiene

CHANGELOG.md

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+# Changelog
+
+All notable changes to this project will be documented in this file.
+
+## [Unreleased]
+
+### Added
+- Professional documentation structure in `docs/`.
+- Internal task tracker using Python and DuckDB.
+- Centralized `Makefile` for project automation.
+- Dockerized development shell.
+- Unique username enforcement on the server.
+- Transaction simulation for messages, reactions, and username changes.
+
+### Fixed
+- DuckDB parameter handling issue in the backend.
+- Reaction animations and persistence.
+- `.gitignore` consolidation.