Implement cooldown feature for nobility advancement

- Added logic in FalukantService to calculate the next available advancement date based on the user's last advancement.
- Updated the frontend to display a cooldown message indicating when the user can next advance in nobility.
- Enhanced the NobilityView component to handle and format the next advancement date appropriately.

frontend/src/i18n/locales/de/falukant.json

@@ -538,7 +538,8 @@
             },
             "advance": {
                 "confirm": "Aufsteigen beantragen"
-            }
+            },
+            "cooldown": "Du kannst frühestens wieder am {date} aufsteigen."
         },
         "reputation": {
             "title": "Reputation",

frontend/src/i18n/locales/en/falukant.json

@@ -41,6 +41,9 @@
                 "raft": "Raft",
                 "sailing_ship": "Sailing ship"
             }
+        },
+        "nobility": {
+            "cooldown": "You can only advance again on {date}."
         }
     }
 }

frontend/src/views/falukant/NobilityView.vue

@@ -23,6 +23,9 @@
               {{ $t('falukant.nobility.nextTitle') }}:
               <strong>{{ $t(`falukant.titles.${gender}.${next.labelTr}`) }}</strong>
             </p>
+            <p v-if="nextAdvanceAt && !canAdvance">
+              {{ $t('falukant.nobility.cooldown', { date: formatDate(nextAdvanceAt) }) }}
+            </p>
             <ul class="prerequisites">
               <li v-for="req in next.requirements" :key="req.titleId">
                   {{ $t(`falukant.nobility.requirement.${req.requirementType}`, { amount: formatCost(req.requirementValue) }) }}
@@ -32,7 +35,6 @@
               <span v-if="!isAdvancing">{{ $t('falukant.nobility.advance.confirm') }}</span>
               <span v-else>{{ $t('falukant.nobility.advance.processing') }}</span>
             </button>
-            <!-- debug state output removed -->
           </div>
         </div>
   
@@ -58,6 +60,7 @@
         ],
         current: { labelTr: '', requirements: [], charactersWithNobleTitle: [] },
         next: { labelTr: '', requirements: [] },
+        nextAdvanceAt: null,
         isAdvancing: false
       };
     },
@@ -67,7 +70,11 @@
         return this.current.charactersWithNobleTitle[0]?.gender || 'male';
       },
       canAdvance() {
-        return true;
+        if (!this.next) return false;
+        if (!this.nextAdvanceAt) return true;
+        const now = new Date();
+        const nextDate = new Date(this.nextAdvanceAt);
+        return nextDate <= now;
       }
     },
     async mounted() {
@@ -101,6 +108,7 @@
           const { data } = await apiClient.get('/api/falukant/nobility');
           this.current = data.current;
           this.next = data.next;
+          this.nextAdvanceAt = data.nextAdvanceAt || null;
         } catch (err) {
           console.error('Error loading nobility:', err);
         }
@@ -124,6 +132,10 @@
       },
       formatCost(val) {
         return new Intl.NumberFormat(navigator.language, { minimumFractionDigits: 2, maximumFractionDigits: 2 }).format(val);
+      },
+      formatDate(isoString) {
+        const d = new Date(isoString);
+        return d.toLocaleDateString();
       }
     }
   };