refactor: restructure registry with auth and agent guidelines

- Add built-in authentication with Apache utils
- Add AGENTS.md for coding guidelines
- Enhance security with authentication enabled by default
- Remove unnecessary template files
- Simplify configuration and setup process

AGENTS.md

@@ -0,0 +1,36 @@
+# Agent Guidelines for Docker Registry Project
+
+## Build & Run
+```bash
+# Build and start services
+docker-compose up -d --build
+
+# Rebuild single service
+docker-compose up -d --build registry
+```
+
+## Code Style
+- YAML files: 2 space indentation
+- Shell scripts: Follow [Google Shell Style Guide](https://google.github.io/styleguide/shellguide.html)
+- Docker best practices:
+  - Use multi-stage builds when possible
+  - Minimize layer size and number
+  - Pin base image versions
+  - Place volatile commands last
+  - One service per container
+
+## Error Handling
+- Shell scripts: Use set -e for strict error handling
+- Log errors to stdout/stderr for Docker logging
+- Follow the fail-fast principle
+- Include error context in messages
+
+## File Structure
+```
+.
+├── config.yml        # Registry configuration
+├── docker-compose.yml # Service orchestration
+├── Dockerfile        # Registry image build
+├── entrypoint.sh    # Container initialization
+└── setup.sh         # Local environment setup
+```