[minimcp] Add ResourceManager for resource registration and execution

- Implement ResourceManager class for managing MCP resource handlers
- Add support for static resources and resource templates (parameterized URIs)
- Add resource registration via decorator (@mcp.resource(uri)) or programmatically
- Support resource listing, reading by URI/name, and removal operations
- Add URI pattern matching and template parameter validation
- Add comprehensive unit test suite

Author: sreenaths