feat: implement core architecture (v0.0.2)

- Implement Config class with YAML loading and environment variable support
- Implement Provider interface and factory pattern
- Implement SiliconFlow provider as example
- Implement Translator core class with prompt management
- Create CLI entry point
- Add configuration template and unit tests
- Update changelog and discussion records

Version: 0.0.2

go.mod

@@ -1,3 +1,5 @@
 module github.com/titor/fanyi
 
 go 1.26.1
+
+require gopkg.in/yaml.v3 v3.0.1 // indirect