fix: stabilize tool-call proxy flow and active page refresh

Fix: proxy compatibility
- Normalize system messages into params.system
- Forward tools and assistant tool calls in Command Code wire format
- Preserve tool-result chaining for OpenAI-compatible tool flows
- Map upstream tool-call events back to OpenAI responses
- Send upstream JSON bodies as UTF-8 bytes and improve upstream error handling

Fix: tui refresh
- Refresh only the active page in the background
- Keep existing content visible during auto-refresh
- Show refresh status in the header and redraw logs live

Chore: logging
- Remove noisy per-request proxy logs
- Make proxy stop idempotent
- Add LogStore version tracking for live UI updates

Author: Khip01