- Add new error messages for fetch operations
- Rename `errInvalidLocationFormat` to `errInvalidLocationFormatKey`
- Use `errors.New` instead of `fmt.Errorf` for fetch errors
- Update Chinese locale with fetch-related error messages
- Add VertexAI error message translations across 10 locale files
- Add Gemini TTS and audio error translations to all locales
- Add AWS Bedrock client error translations to all locales
- Add fetch plugin error message translations to all locales
- Replace hardcoded English strings with `i18n.T()` calls in Bedrock plugin
- Replace hardcoded English strings with `i18n.T()` calls in Gemini plugin
- Replace hardcoded English strings with `i18n.T()` calls in VertexAI plugin
- Replace hardcoded English strings with `i18n.T()` calls in fetch plugin
- Use `errors.New` instead of `fmt.Errorf` for non-formatted error strings
### CHANGES
- Introduce `cmd` directory for all main application binaries.
- Move all Go packages into the `internal` directory.
- Rename the `restapi` package to `server` for clarity.
- Consolidate patterns and strategies into a new `data` directory.
- Group all auxiliary scripts into a new `scripts` directory.
- Move all documentation and images into a `docs` directory.
- Update all Go import paths to reflect the new structure.
- Adjust CI/CD workflows and build commands for new layout.
