feat: allow drafting messages while response is streaming in AskBarView

[quiet-node]

Allow users to continue composing messages while an assistant response is streaming.

Details:

• AskBarView preserves local input as a "draft" so users can type and edit while tokens arrive.
• Input submit is decoupled from the streaming lifecycle so drafts are not cleared when streaming begins.
• Adds unit/integration tests covering drafting behavior during streaming.

Changed files:

• src/view/AskBarView.tsx
• src/view/tests/AskBarView.test.tsx
• src/tests/App.test.tsx