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/models/schemas.py

@@ -0,0 +1,32 @@
+"""Pydantic models for NanoClaude API."""
+
+from __future__ import annotations
+
+from enum import Enum
+
+from pydantic import BaseModel
+
+
+class JobStatus(str, Enum):
+    queued = "queued"
+    processing = "processing"
+    completed = "completed"
+    failed = "failed"
+    cancelled = "cancelled"
+
+
+class ChatRequest(BaseModel):
+    message: str
+
+
+class ChatResponse(BaseModel):
+    job_id: str
+
+
+class CancelResponse(BaseModel):
+    status: str
+
+
+class SSEEvent(BaseModel):
+    event: str  # ack | processing | result | error | done
+    data: dict