feat(falukant): refine tax calculation logic to handle political office exemptions

- Updated the tax calculation in FalukantService to ensure no exemptions are applied for political offices, streamlining the cumulative tax query.
- Enhanced the SQL query to accurately compute cumulative tax while excluding exempted ancestor levels based on office, improving overall accuracy in tax assessments.

backend/services/falukantService.js

@@ -355,7 +355,12 @@ async function calcRegionalSellPrice(product, knowledgeFactor, regionId, worthPe
         // If chancellor, exempt all region types -> tax = 0
         if (hasChancellor) return 0;
 
-        // Now compute cumulative tax but exclude regions whose regionType.labelTr is in exemptTypes
+        // No exemptions from political offices -> use normal cumulative tax query.
+        if (exemptTypes.size === 0) {
+            return await getCumulativeTaxPercent(regionId);
+        }
+
+        // Compute cumulative tax excluding ancestor levels that are exempted by office.
         const rows = await sequelize.query(
             `WITH RECURSIVE ancestors AS (
                 SELECT r.id, r.parent_id, r.tax_percent, rt.label_tr as region_type
@@ -368,7 +373,11 @@ async function calcRegionalSellPrice(product, knowledgeFactor, regionId, worthPe
                 JOIN falukant_type.region_type rt2 ON rt2.id = reg.region_type_id
                 JOIN ancestors a ON reg.id = a.parent_id
             )
-            SELECT COALESCE(SUM(CASE WHEN :exempt_types::text[] && ARRAY[region_type] THEN 0 ELSE tax_percent END),0) AS total FROM ancestors;`,
+            SELECT COALESCE(
+              SUM(CASE WHEN region_type IN (:exempt_types) THEN 0 ELSE tax_percent END),
+              0
+            ) AS total
+            FROM ancestors;`,
             {
                 replacements: { id: regionId, exempt_types: Array.from(exemptTypes) },
                 type: sequelize.QueryTypes.SELECT