feat(p4): content analysis service with Neo4j knowledge graph and ClickHouse analytics

P4 阶段交付物：
- services/content: 内容资源服务（NestJS）
  - textbooks: 教材 CRUD + 知识图谱绑定
  - config/neo4j.ts: Neo4j driver 单例
  - textbooks.service.ts: MySQL CRUD + Neo4j 知识图谱（createKnowledgeGraph/getPrerequisites）
  - package.json: 补充 @opentelemetry/sdk-node + exporter-trace-otlp-http
- services/data-ana: 数据分析服务（Python FastAPI）
  - main.py: FastAPI + /healthz + class_performance + student_weakness 骨架
  - clickhouse_client.py: ClickHouse 客户端封装
  - config.py: 环境变量配置
- packages/shared-proto/proto/content.proto: TextbookService + KnowledgeGraphService 契约
- packages/shared-proto/proto/analytics.proto: AnalyticsService 契约（class_performance/student_weakness）

services/data-ana/Dockerfile

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+FROM python:3.12-slim
+WORKDIR /app
+RUN pip install uv
+COPY pyproject.toml .
+RUN uv sync --no-dev
+COPY src ./src
+EXPOSE 3006
+CMD ["uv", "run", "uvicorn", "src.data_ana.main:app", "--host", "0.0.0.0", "--port", "3006"]

services/data-ana/README.md

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+# data-ana 数据分析服务
+
+> 版本：0.1（P4 骨架）
+> 端口：3006
+
+## 职责
+
+数据分析限界上下文（Python 实现），消费 core-edu 与 content 的领域事件，
+构建 ClickHouse 学情宽表，计算知识点掌握度。
+对外提供学情仪表盘查询、班级/年级/学校维度报表、个性化推荐数据支撑。
+
+## 技术栈
+
+- Python 3.12+ / FastAPI 0.115+
+- clickhouse-connect（ClickHouse 宽表查询）
+- pydantic + pydantic-settings（运行时校验与配置）
+- structlog（结构化日志）
+- prometheus-client（指标）
+- OpenTelemetry（分布式追踪）
+
+## 开发
+
+```bash
+uv sync
+uv run uvicorn src.data_ana.main:app --host 0.0.0.0 --port 3006 --reload
+```
+
+## 配置
+
+| 变量 | 默认值 | 说明 |
+|------|--------|------|
+| `PORT` | 3006 | 服务端口 |
+| `CLICKHOUSE_HOST` | localhost | ClickHouse 主机 |
+| `CLICKHOUSE_PORT` | 8123 | ClickHouse HTTP 端口 |
+| `CLICKHOUSE_DATABASE` | edu_analytics | ClickHouse 数据库 |
+| `OTEL_ENDPOINT` | http://localhost:4318 | OpenTelemetry 端点 |
+| `LOG_LEVEL` | info | 日志级别 |
+
+## 模块结构
+
+```
+src/data_ana/
+├─ __init__.py
+├─ main.py              # FastAPI 入口（健康检查 + 分析端点骨架）
+├─ config.py            # pydantic-settings 配置
+└─ clickhouse_client.py # ClickHouse 客户端单例
+```
+
+## 关键端点
+
+- `GET /healthz` 健康检查
+- `GET /metrics` Prometheus 指标
+- `GET /analytics/class/{class_id}/performance` 班级成绩分析（P4 骨架）
+- `GET /analytics/student/{student_id}/weakness` 学生薄弱知识点分析（P4 骨架）
+
+## 对外契约
+
+gRPC 服务 `AnalyticsService` 定义见 `packages/shared-proto/proto/analytics.proto`。

services/data-ana/pyproject.toml

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+[project]
+name = "data-ana-service"
+version = "0.1.0"
+description = "数据分析服务 - ClickHouse + 学习分析"
+requires-python = ">=3.12"
+dependencies = [
+    "fastapi>=0.115.0",
+    "uvicorn[standard]>=0.30.0",
+    "clickhouse-connect>=0.7.0",
+    "pydantic>=2.9.0",
+    "pydantic-settings>=2.5.0",
+    "opentelemetry-api>=1.27.0",
+    "opentelemetry-sdk>=1.27.0",
+    "opentelemetry-instrumentation-fastapi>=0.48b0",
+    "prometheus-client>=0.20.0",
+    "structlog>=24.4.0",
+]
+
+[tool.ruff]
+line-length = 100
+target-version = "py312"
+
+[tool.ruff.lint]
+select = ["E", "F", "I", "N", "W", "UP", "B", "SIM"]

services/data-ana/src/data_ana/clickhouse_client.py

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+"""ClickHouse 客户端."""
+import clickhouse_connect
+from .config import settings
+
+_client = None
+
+
+def get_client():
+    """获取 ClickHouse 客户端."""
+    global _client
+    if _client is None:
+        _client = clickhouse_connect.get_client(
+            host=settings.clickhouse_host,
+            port=settings.clickhouse_port,
+            database=settings.clickhouse_database,
+        )
+    return _client
+
+
+async def close_client() -> None:
+    """关闭客户端."""
+    global _client
+    if _client:
+        _client.close()
+        _client = None

services/data-ana/src/data_ana/config.py

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+"""配置管理."""
+from pydantic_settings import BaseSettings
+
+
+class Settings(BaseSettings):
+    """应用配置."""
+
+    port: int = 3006
+    clickhouse_host: str = "localhost"
+    clickhouse_port: int = 8123
+    clickhouse_database: str = "edu_analytics"
+    otel_endpoint: str = "http://localhost:4318"
+    log_level: str = "info"
+
+    model_config = {"env_file": ".env", "env_prefix": ""}
+
+
+settings = Settings()

services/data-ana/src/data_ana/main.py

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+"""数据分析服务入口."""
+from contextlib import asynccontextmanager
+from fastapi import FastAPI
+from opentelemetry import trace
+from opentelemetry.sdk.trace import TracerProvider
+from opentelemetry.sdk.trace.export import BatchSpanProcessor
+from opentelemetry.exporter.otlp.proto.http.trace_exporter import OTLPSpanExporter
+from prometheus_client import make_asgi_app
+import structlog
+
+logger = structlog.get_logger()
+tracer = trace.get_tracer(__name__)
+
+
+def init_tracer() -> None:
+    """初始化 OpenTelemetry."""
+    provider = TracerProvider()
+    exporter = OTLPSpanExporter(endpoint="http://localhost:4318/v1/traces")
+    provider.add_span_processor(BatchSpanProcessor(exporter))
+    trace.set_tracer_provider(provider)
+
+
+@asynccontextmanager
+async def lifespan(app: FastAPI):
+    """应用生命周期."""
+    init_tracer()
+    logger.info("data-ana service starting")
+    yield
+    logger.info("data-ana service stopping")
+
+
+app = FastAPI(
+    title="Data Analytics Service",
+    version="0.1.0",
+    lifespan=lifespan,
+)
+
+# Prometheus 指标
+app.mount("/metrics", make_asgi_app())
+
+
+@app.get("/healthz")
+async def healthz():
+    """健康检查."""
+    return {"status": "ok", "service": "data-ana"}
+
+
+@app.get("/analytics/class/{class_id}/performance")
+async def class_performance(class_id: str):
+    """班级成绩分析."""
+    with tracer.start_as_current_span("class_performance"):
+        # P4 骨架：从 ClickHouse 查询分析数据
+        return {
+            "success": True,
+            "data": {
+                "classId": class_id,
+                "averageScore": 0,
+                "passRate": 0,
+                "message": "P4 skeleton - ClickHouse integration pending",
+            },
+        }
+
+
+@app.get("/analytics/student/{student_id}/weakness")
+async def student_weakness(student_id: str):
+    """学生薄弱知识点分析."""
+    with tracer.start_as_current_span("student_weakness"):
+        return {
+            "success": True,
+            "data": {
+                "studentId": student_id,
+                "weakPoints": [],
+                "message": "P4 skeleton - weakness analysis pending",
+            },
+        }