feat: Add comprehensive documentation suite and reorganize project structure

- Created complete documentation in docs/ directory
- Added PROJECT_OVERVIEW.md with feature highlights and getting started guide
- Added ARCHITECTURE.md with system design and technical details
- Added SECURITY.md with comprehensive security implementation guide
- Added DEVELOPMENT.md with development workflows and best practices
- Added DEPLOYMENT.md with production deployment instructions
- Added API.md with complete REST API documentation
- Added CONTRIBUTING.md with contribution guidelines
- Added CHANGELOG.md with version history and migration notes
- Reorganized all documentation files into docs/ directory for better organization
- Updated README.md with proper documentation links and quick navigation
- Enhanced project structure with professional documentation standards

f_scripts/shared/flagicon/flags/1x1/sl.svg

@@ -0,0 +1,12 @@
+<svg xmlns="http://www.w3.org/2000/svg" height="512" width="512" viewBox="0 0 512 512">
+  <defs>
+    <clipPath id="a">
+      <rect width="384" height="512" rx="4.627" ry="7.628"/>
+    </clipPath>
+  </defs>
+  <g transform="matrix(1.33333 0 0 1 0 0)" clip-path="url(#a)" fill-rule="evenodd">
+    <path fill="#0000cd" d="M0 341.7h512V512H0z"/>
+    <path fill="#fff" d="M0 171.4h512v170.3H0z"/>
+    <path fill="#00cd00" d="M0 0h512v171.4H0z"/>
+  </g>
+</svg>