feat(chat): insert file path into input on non-image drag-and-drop

[BowgartField]

Summary

• Previously, dropping non-image files into the chat window showed an error toast ("Only images are accepted")
• Now, non-image file paths are inserted (double-quoted) directly into the chat input, so Claude can reference them
• Images continue to be processed as attachments as before

Changes

• useDragAndDropImages.ts — Collect non-image paths in otherPaths array instead of showing error/warning toasts; expose droppedFilePaths and clearDroppedFilePaths
• ChatWindow.tsx — Wire new props from the hook to ChatInput
• ChatInput.tsx — New droppedFilePaths prop + useEffect that inserts quoted paths into the textarea and updates draft state

Test plan

• Drop a non-image file (e.g. .rs, .txt, .json) → its absolute path appears quoted in the input
• Drop an image (PNG, JPEG, etc.) → still processed as image attachment
• Drop a mix of images and non-images → images attached, non-image paths inserted
• Drop multiple non-image files → all paths inserted space-separated