feat(core): register currency router in main.py

app/main.py

@@ -37,6 +37,7 @@ from app.routes import (
     tenants,
     users,
     workflows,
+    currencies,
 )
 
 
@@ -186,6 +187,7 @@ def create_app() -> FastAPI:
     app.include_router(plugins.router)
     app.include_router(ai_copilot.router)
     app.include_router(workflows.router)
+    app.include_router(currencies.router)
 
     # ── Register plugin routes (before SPA catch-all) ────────────────
     registry = get_registry()