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/getting-started/cms-quick-start.md

@@ -184,7 +184,7 @@ Existing pages are never overwritten.
 For complete CMS documentation, see:
 - [CMS Feature Documentation](../features/content-management-system.md)
 - [CMS Implementation Guide](../features/cms-implementation-guide.md)
-- [Database Seeder Guide](../development/database-seeder/DATABASE_SEEDER_DOCUMENTATION.md)
+- [Database Seeder Guide](../development/database-seeder/database-seeder-documentation.md)
 
 ## Troubleshooting