feat: AI 서비스 및 AI 어시스턴트 전용 페이지 추가

- ai-service: Ollama 기반 AI 서비스 (분류, 시맨틱 검색, RAG Q&A, 패턴 분석)
- AI 어시스턴트 페이지: 채팅형 Q&A, 시맨틱 검색, 패턴 분석, 분류 테스트
- 권한 시스템에 ai_assistant 페이지 등록 (기본 비활성)
- 기존 페이지에 AI 기능 통합 (대시보드, 수신함, 관리함)
- docker-compose, gateway, nginx 설정 업데이트

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

ai-service/services/ollama_client.py

@@ -0,0 +1,57 @@
+import httpx
+from config import settings
+
+
+class OllamaClient:
+    def __init__(self):
+        self.base_url = settings.OLLAMA_BASE_URL
+        self.timeout = httpx.Timeout(float(settings.OLLAMA_TIMEOUT), connect=10.0)
+
+    async def generate_embedding(self, text: str) -> list[float]:
+        async with httpx.AsyncClient(timeout=self.timeout) as client:
+            response = await client.post(
+                f"{self.base_url}/api/embeddings",
+                json={"model": settings.OLLAMA_EMBED_MODEL, "prompt": text},
+            )
+            response.raise_for_status()
+            return response.json()["embedding"]
+
+    async def batch_embeddings(self, texts: list[str]) -> list[list[float]]:
+        results = []
+        for text in texts:
+            emb = await self.generate_embedding(text)
+            results.append(emb)
+        return results
+
+    async def generate_text(self, prompt: str, system: str = None) -> str:
+        messages = []
+        if system:
+            messages.append({"role": "system", "content": system})
+        messages.append({"role": "user", "content": prompt})
+        async with httpx.AsyncClient(timeout=self.timeout) as client:
+            response = await client.post(
+                f"{self.base_url}/api/chat",
+                json={
+                    "model": settings.OLLAMA_TEXT_MODEL,
+                    "messages": messages,
+                    "stream": False,
+                    "options": {"temperature": 0.3, "num_predict": 2048},
+                },
+            )
+            response.raise_for_status()
+            return response.json()["message"]["content"]
+
+    async def check_health(self) -> dict:
+        try:
+            async with httpx.AsyncClient(timeout=httpx.Timeout(5.0)) as client:
+                response = await client.get(f"{self.base_url}/api/tags")
+                models = response.json().get("models", [])
+                return {
+                    "status": "connected",
+                    "models": [m["name"] for m in models],
+                }
+        except Exception:
+            return {"status": "disconnected"}
+
+
+ollama_client = OllamaClient()