chore: modular monolith folder split (no behavior change)

app/api/dashboard.py

@@ -0,0 +1,13 @@
+"""
+API Aggregation Layer - Dashboard endpoints
+Composes data from multiple feature modules
+"""
+from fastapi import APIRouter
+
+router = APIRouter(prefix="/api/dashboard", tags=["dashboard-aggregation"])
+
+# TODO: Implement aggregation endpoints that combine data from
+# app.seismo and app.slm modules
+
+# For now, individual feature modules expose their own APIs directly
+# Future: Add cross-feature aggregation here