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.