feat: Initial CBPOA commit — 武汉儿童呼吸疾病风险评估系统

Context: Build a spatial risk assessment system correlating air quality
data with children's respiratory disease incidence across Wuhan.

Approach: FastAPI backend serving PostGIS spatial queries, React
frontend with Deck.gl maps, and a PyTorch SpatialTemporalGCN pipeline
for multi-day (1d/3d/7d) risk prediction.

Changes:
- backend/ — FastAPI API with auth (JWT), alerts, risk analysis,
  geocoded case data, grid statistics, and report endpoints
- frontend/ — React dashboard with interactive risk maps, alert
  monitoring, district comparison charts, and timeline player
- models/ — SpatialTemporalGCN model with trained weights and ONNX
  export for inference
- scripts/ — ETL pipeline for weather + medical data, grid generation,
  feature engineering, training, and daily inference
- deploy/ — Docker Compose configs for backend, frontend, and MLflow
- docs/ — API docs, deployment guide, user guide, and code review

Impact: Enables spatial risk visualization, alert monitoring, and
ML-driven health risk forecasting for environmental health teams.

backend/auth/router.py

@@ -0,0 +1,34 @@
+"""Authentication endpoints: login, register, whoami."""
+from fastapi import APIRouter, Depends, HTTPException, status
+
+from .models import UserCreate, UserLogin, Token, UserOut
+from .service import authenticate_user, create_access_token, create_user
+from .dependencies import get_current_user
+
+router = APIRouter(prefix="/api/auth", tags=["auth"])
+
+
+@router.post("/login", response_model=Token)
+async def login(body: UserLogin):
+    if not authenticate_user(body.username, body.password):
+        raise HTTPException(
+            status_code=status.HTTP_401_UNAUTHORIZED,
+            detail="Incorrect username or password",
+        )
+    token = create_access_token({"sub": body.username})
+    return Token(access_token=token)
+
+
+@router.post("/register", response_model=UserOut, status_code=status.HTTP_201_CREATED)
+async def register(body: UserCreate):
+    if not create_user(body.username, body.password):
+        raise HTTPException(
+            status_code=status.HTTP_409_CONFLICT,
+            detail="Username already exists",
+        )
+    return UserOut(username=body.username)
+
+
+@router.get("/me", response_model=UserOut)
+async def me(username: str = Depends(get_current_user)):
+    return UserOut(username=username)