fix(falukant): validate office term length and adjust term end calculation

- Added validation for office term length to ensure it is a positive finite number, throwing an error for invalid values.
- Updated the calculation of the term end date to use the term length in days instead of years, aligning with the expected data format.

backend/services/falukantPoliticalPowersService.js

@@ -457,8 +457,14 @@ class FalukantPoliticalPowersService {
         }
 
         const start = new Date();
+        const termDays = Number(officeType.termLength);
+        if (!Number.isFinite(termDays) || termDays <= 0) {
+            const err = new Error('invalid_office_term_length');
+            err.status = 500;
+            throw err;
+        }
         const end = new Date(start);
-        end.setFullYear(end.getFullYear() + (officeType.termLength || 4));
+        end.setDate(end.getDate() + termDays);
 
         let newOffice;
         await sequelize.transaction(async (t) => {

backend/services/falukantService.js

@@ -6388,13 +6388,14 @@ class FalukantService extends BaseService {
         return offices.map((office) => {
             const o = office.get({ plain: true });
 
-            // Enddatum der Amtszeit berechnen: Start = createdAt, Dauer = termLength Jahre
+            // Enddatum der Amtszeit: wie DB/C++-Worker — Start + termLength Kalendertage
+            // (falukant_type.political_office_type.term_length ist in Tagen, vgl. politics_worker.h)
             let termEnds = null;
-            if (o.createdAt && o.type && typeof o.type.termLength === 'number') {
+            if (o.createdAt && o.type && typeof o.type.termLength === 'number' && o.type.termLength > 0) {
                 const start = new Date(o.createdAt);
                 if (!Number.isNaN(start.getTime())) {
                     const end = new Date(start);
-                    end.setFullYear(end.getFullYear() + o.type.termLength);
+                    end.setDate(end.getDate() + o.type.termLength);
                     termEnds = end;
                 }
             }