The sessions.reset RPC only reset the native session store, leaving the
Claude CLI-backed history (.jsonl + CLAUDE.md) in place. The /reset chat
command already clears it via providers.ResetCLISession, so RPC callers
got an incomplete reset for claude-cli agents — stale history was resumed
on the next turn.
Mirror the chat path by calling ResetCLISession from handleReset. It is a
no-op when the CLI provider is unused. The call is wired through an
overridable package var so the behavior can be regression-tested.
