Organize documentation: move all .md files to docs/ folder

- Move all markdown files except README.md to docs/ folder

- Consolidate deployment docs into docs/DEPLOYMENT.md

- Consolidate troubleshooting docs into docs/TROUBLESHOOTING.md

- Rename README_SERVER.md to docs/DEVELOPMENT.md

- Create docs/README.md as documentation index

- Remove outdated documentation files

- Keep README.md in root as main project entry point

Author: mytherapy-coding