feat: NanoClaude Phase 1 — 비동기 job 기반 AI Gateway 코어 구현

POST /chat → job_id ACK, GET /chat/{job_id}/stream → SSE 스트리밍,
EXAONE Ollama adapter, JobManager, StateStream, Worker 구조

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

nanoclaude/services/worker.py

@@ -0,0 +1,65 @@
+"""Worker — background task that drives EXAONE call and pushes SSE events."""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+
+from models.schemas import JobStatus
+from services.exaone_adapter import stream_chat
+from services.job_manager import Job, job_manager
+from services.state_stream import state_stream
+
+logger = logging.getLogger(__name__)
+
+# 무응답 방지: 3~5초 간격으로 processing heartbeat
+HEARTBEAT_INTERVAL = 4.0
+
+
+async def run(job: Job) -> None:
+    """EXAONE 호출 → SSE 이벤트 발행."""
+    try:
+        # --- ACK ---
+        await state_stream.push(job.id, "ack", {"message": "요청을 확인했습니다. 분석을 시작합니다."})
+        job_manager.set_status(job.id, JobStatus.processing)
+
+        # --- Processing + Streaming ---
+        await state_stream.push(job.id, "processing", {"message": "EXAONE 모델이 응답을 생성하고 있습니다..."})
+
+        collected: list[str] = []
+        last_heartbeat = asyncio.get_event_loop().time()
+
+        async for chunk in stream_chat(job.message):
+            if job.status == JobStatus.cancelled:
+                logger.info("Job %s cancelled during streaming", job.id)
+                await state_stream.push(job.id, "error", {"message": "작업이 취소되었습니다."})
+                return
+
+            collected.append(chunk)
+
+            # Stream partial result
+            await state_stream.push(job.id, "result", {"content": chunk})
+
+            # Heartbeat: 긴 침묵 방지
+            now = asyncio.get_event_loop().time()
+            if now - last_heartbeat >= HEARTBEAT_INTERVAL:
+                await state_stream.push(job.id, "processing", {"message": "응답 생성 중..."})
+                last_heartbeat = now
+
+        # --- Complete ---
+        if not collected:
+            job_manager.set_status(job.id, JobStatus.failed)
+            await state_stream.push(job.id, "error", {"message": "EXAONE으로부터 응답을 받지 못했습니다."})
+        else:
+            job_manager.set_status(job.id, JobStatus.completed)
+            await state_stream.push(job.id, "done", {"message": "완료"})
+
+    except asyncio.CancelledError:
+        job_manager.set_status(job.id, JobStatus.cancelled)
+        await state_stream.push(job.id, "error", {"message": "작업이 취소되었습니다."})
+    except Exception:
+        logger.exception("Worker failed for job %s", job.id)
+        job_manager.set_status(job.id, JobStatus.failed)
+        await state_stream.push(job.id, "error", {"message": "내부 오류가 발생했습니다."})
+    finally:
+        await state_stream.push_done(job.id)