Extracted the `Gson()` instantiation in `ChatViewModel.kt` to a companion object to avoid creating a new `Gson` instance on every `ToolStart` and `ToolComplete` event handler call. This change reduces garbage collection pressure by caching reflection setup, type adapters, and factories.
Impact:
- Reduces memory allocations and CPU cycles during multi-step tool chains and streaming.
- Safely maintains existing parsing behavior while addressing the `PERF-03` review finding.
Closes#271
M57
d9c7471350