refactor: standardize markdown file naming to kebab-case convention

Renamed all documentation files to follow kebab-case naming standard:
- UPPERCASE files → lowercase (e.g., RBAC.md → rbac.md)
- snake_case files → kebab-case (e.g., icons_guide.md → icons-guide.md)
- SCREAMING_SNAKE_CASE → kebab-case (e.g., DATABASE_SETUP_GUIDE.md → database-setup-guide.md)

Files renamed (15 total):
API Documentation:
  - api/RBAC.md → api/rbac.md

Architecture:
  - architecture/API_CONSOLIDATION_PROPOSAL.md → api-consolidation-proposal.md
  - architecture/API_MIGRATION_STATUS.md → api-migration-status.md

Development:
  - development/AUTH_DEPENDENCIES_GUIDE.md → auth-dependencies-guide.md
  - development/CUSTOMER_AUTHENTICATION_IMPLEMENTATION.md → customer-authentication-implementation.md
  - development/CUSTOMER_AUTH_SUMMARY.md → customer-auth-summary.md
  - development/icons_guide.md → icons-guide.md

Database Seeder:
  - database-seeder/DATABASE_INIT_GUIDE.md → database-init-guide.md
  - database-seeder/DATABASE_QUICK_REFERENCE_GUIDE.md → database-quick-reference-guide.md
  - database-seeder/DATABASE_SEEDER_DOCUMENTATION.md → database-seeder-documentation.md
  - database-seeder/MAKEFILE_DATABASE_SEEDER.md → makefile-database-seeder.md

Error Rendering:
  - error-rendering/ERROR_RENDERING_DEVELOPER_DOCUMENTATION.md → error-rendering-developer-documentation.md
  - error-rendering/HTML_ERROR_RENDERING_FLOW_DIAGRAM.md → html-error-rendering-flow-diagram.md

Getting Started:
  - getting-started/DATABASE_QUICK_REFERENCE.md → database-quick-reference.md
  - getting-started/DATABASE_SETUP_GUIDE.md → database-setup-guide.md

Updates:
- Updated all references in mkdocs.yml
- Updated all cross-references in markdown files
- Verified mkdocs builds without warnings or errors

Standard: Use kebab-case (lowercase-with-hyphens) for all markdown files

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

docs/frontend/overview.md

@@ -349,7 +349,7 @@ For detailed information about the design patterns used across all frontends, se
 - **[Pagination System](shared/pagination.md)** - Pagination implementation
 - **[Sidebar Navigation](shared/sidebar.md)** - Sidebar setup guide
 - **[Logging System](shared/logging.md)** - Frontend logging configuration
-- **[Icons Guide](../development/icons_guide.md)** - Icon system usage
+- **[Icons Guide](../development/icons-guide.md)** - Icon system usage
 
 ---
 
@@ -497,7 +497,7 @@ For detailed information about the design patterns used across all frontends, se
 2. Study the page template guide for that frontend
 3. Review existing code examples (`dashboard.js` is the best)
 4. Check the [Shared Components](shared/ui-components.md) documentation
-5. Review the [Icons Guide](../development/icons_guide.md)
+5. Review the [Icons Guide](../development/icons-guide.md)
 6. Copy templates and start building!
 
 Questions? Check the detailed architecture docs or review existing implementations in the codebase.