Fix backfill logic in prompt enable workflow:
- Prioritize backfilling live file content to currently enabled prompt (prevent data loss)
- Create backup only when no enabled prompt exists and content is new (avoid duplicate backups)
- Implement staged persistence (save after backfill + save after enable)
- Add explicit logging for backfill/backup operations
Also simplify string formatting in prompt_files.rs with inline format strings.
Address code review feedback for PR #214:
- Replace hardcoded Chinese strings with English in auto-imported prompts
- Prompt name: "Auto-imported Prompt" instead of "初始提示词"
- Description: "Automatically imported on first launch"
- Remove panic risk by replacing expect() with proper error propagation
- Use AppError::localized for bilingual error messages
- Extract get_base_dir_with_fallback() helper to eliminate code duplication
- Update test assertions to match new English strings
- Suppress false-positive dead_code warning on TempHome.dir field
All 5 tests passing with zero compiler warnings.
- Extract prompt file path logic to dedicated prompt_files module
- Refactor PromptService to use centralized path resolution
- Implement auto-import for existing prompt files on first startup
- Add comprehensive unit tests for auto-import functionality
YoVinchen