feat: Persist initial capex calculations and enhance navigation links in UI

routes/calculations.py

@@ -805,7 +805,7 @@ def capex_form(
 )
 async def capex_submit(
     request: Request,
-    _: User = Depends(require_authenticated_user),
+    current_user: User = Depends(require_authenticated_user),
     uow: UnitOfWork = Depends(get_unit_of_work),
     project_id: int | None = Query(
         None, description="Optional project identifier"),
@@ -877,6 +877,15 @@ async def capex_submit(
         uow=uow, project_id=project_id, scenario_id=scenario_id
     )
 
+    _persist_capex_snapshots(
+        uow=uow,
+        project=project,
+        scenario=scenario,
+        user=current_user,
+        request_model=request_model,
+        result=result,
+    )
+
     if wants_json:
         return JSONResponse(
             status_code=status.HTTP_200_OK,