Add native Assist streaming for OpenClaw conversation

[lukcz]

Summary

• migrate the OpenClaw conversation agent to an entity-backed streaming agent
• feed OpenClaw SSE deltas into Home Assistant ChatLog and build the final result via HA helpers
• keep the existing automation event, session resolution, prompts, heuristics, and add fallback plus tests

Testing

• pytest -q tests/test_conversation_streaming.py

[chatgpt-codex-connector]

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[lukcz]

Follow-up update pushed to this PR.

What changed:

• refresh the Assist pipeline selection before every send in openclaw-chat-card.js
• bump the card resource URL/version so browsers pick up the updated JS

Why:

• the custom card could cache an early pipeline lookup and fall back to the legacy path even after the OpenClaw Assist pipeline became available
• this was reproduced and then verified in-browser with intent-progress events arriving through assist_pipeline/run

New commit on this PR branch: 5a2eb4a.