Continue conversation after Assist tool calls

[itsreverence]

Summary

• Track whether a Codex streaming turn requested a Home Assistant tool call.
• Continue the conversation loop after tool calls so the model sees returned tool results and produces the final answer in the same Assist turn.
• Keep existing stop behavior for turns that only stream text.

Why

Home Assistant may consume/store script tool results immediately, leaving chat_log.unresponded_tool_results empty by the time Codex Assist checks it. In that case Codex Assist stopped after the tool call and the UI stayed at ... until the next user message.

Tracking whether the model requested a tool call during the stream is the better signal that a follow-up model pass is needed.

Verification

• uv run ruff check .
• uv run pytest -q

[itsreverence]

Review note: I reviewed the tool-call loop fix and reran local verification. The change is narrowly scoped: it keeps text-only turns stopping normally, but uses the streamed tool-call event as the signal to continue into the follow-up model pass after HA returns tool results. CI is green and local ruff/tests pass.