fix(claude_code): streaming Stage 6 emits message_complete with response (2.0.2)

[CocoRoF]

Summary

Streaming Stage 6 calls with provider=claude_code_cli failed with APIError("Stream ended without message_complete") for every session. Symptom in a Geny pipeline run:

→ s06_api
✗ s06_api: Stream ended without message_complete
Pipeline error: Stream ended without message_complete

Root cause

ClaudeCodeCLIClient.create_message_stream passed the translator's bare {"type": "message_complete"} straight through. The s06_api default stage's _call_streaming reads chunk["response"] to build the assistant message; with no response field on the envelope, response stayed None and the post-loop guard raised:

async for chunk in stream:
    if chunk_type == "message_complete":
        response = chunk["response"]
    elif chunk_type == "text_delta" and chunk.get("text"):
        state.add_event("text.delta", {"text": chunk["text"]})

if response is None:
    raise APIError("Stream ended without message_complete", ...)

Anthropic / OpenAI / Google clients all emit {"type": "message_complete", "response": APIResponse} — the CLI client was the lone outlier.

Fix

create_message_stream now accumulates text / thinking / tool_use blocks + the final result envelope's usage as canonical events flow, then yields one terminal message_complete carrying an assembled APIResponse. Mirrors the contract of every SDK client and reuses the same parsing logic assemble_response_from_stream_json uses for the non-streaming path. Per-line text_delta / content_block_stop / result events still pass through unchanged.

Suppresses the translator's bare message_complete so callers don't see a half-populated event before the real one — there's only ever one terminal envelope.

Test plan

• test_create_message_stream_message_complete_carries_response (new) — single terminal envelope, populated response, stop_reason, usage, model
• test_create_message_stream_yields_text_deltas (existing) — per-line deltas + final result + complete all still surface
• Full tests/llm_client/ suite — 184/184 pass
• Manual verify on Geny prod once 2.0.2 is published + pinned

Release

2.0.2. Migration: none — strictly additive change. Code that didn't use claude_code_cli for s06 sees no difference; code that did was broken before this PR and works after.