- Remove PromptTemplateConfig component and related files
- Remove TemplatePickerPanel and template editing functionality
- Remove PromptTemplateService and PromptTemplateAPI
- Remove prompt template types and parser utilities
- Remove prompt template related API endpoints in Rust backend
- Remove prompt template i18n translation files
- Clean up references in ChatInput, PersonaView, and settings

This simplifies the codebase by removing unused prompt template functionality.