feat(FalukantService, CreateBranchDialog): implement dynamic branch cost calculation

- Added new constants and methods in FalukantService to calculate branch action costs based on owned branch types, enhancing the cost management logic.
- Updated the CreateBranchDialog to utilize the new cost calculation, ensuring accurate display of branch creation costs based on user-owned branches.
- Improved the handling of branch type costs, allowing for a more flexible and responsive user experience when creating and upgrading branches.

frontend/src/dialogues/falukant/CreateBranchDialog.vue

@@ -257,6 +257,9 @@
       },
   
       computeBranchCost(type) {
+        if (Number.isFinite(Number(type?.createCost))) {
+          return Math.round(Number(type.createCost) * 100) / 100;
+        }
         const total = this.cities.reduce((sum, city) => sum + city.branches.length, 0);
         const factor = Math.pow(Math.max(total, 1), 1.2);
         const raw = type.baseCost * factor;