Standardize message extraction logic to use promptContent field for user roles and content field for assistant roles. Update all AI provider implementations (Claude, OpenAI, Gemini) and corresponding tests. Remove trailing space insertion in ChatInput and clean up minor formatting issues.
Replace getNodeAtCursorPosition with getElementBeforeCursor for more robust element detection before cursor. Add cursor position validation after deletions to prevent cursor from ending up inside contenteditable="false" elements. Remove unused helper methods and reorganize code structure.
refactor: rename type interfaces to use I prefix convention
Standardize naming by adding I prefix to all interface types across the codebase (StreamChunk → IStreamChunk, SearchMatch → ISearchMatch, etc.). Also rename conversationStore.ts to ConversationStore.ts for consistency.
Move input field, submit button, and edit mode toggle from ChatWindow into a new ChatInput component to improve separation of concerns and code maintainability.
