Add draft read/write endpoints decoupled from window focus #1
Description
Currently, the only way to set a draft is via POST /v1/focus with draftText, which also steals window focus and navigates to the target chat. There is no way to read existing drafts, and no way to set a draft without the focus/navigation side effect.
Proposed addition: GET/PUT /v1/chats/{chatID}/draft endpoints that read and write draft text independently of window focus.
Use case: AI agents (via MCP or REST) composing messages for user review. Right now, preparing a draft in chat A interrupts the user if they're looking at chat B. A decoupled draft endpoint would let agents stage messages silently across multiple chats.