feat(club): enhance access request functionality in ClubView

- Added a visual indicator for access requests with a new message when access is requested.
- Disabled the request access button once the request has been made to prevent duplicate submissions.
- Improved error handling in the requestAccess method to manage access request status more effectively.

frontend/src/views/ClubView.vue

@@ -23,7 +23,10 @@
         </div>
         <div v-else>
             <div>{{ $t('club.noAccess') }}</div>
-            <button @click="requestAccess">{{ $t('club.requestAccess') }}</button>
+            <div v-if="accessRequested" class="access-requested">
+                {{ $t('club.accessRequested') }}
+            </div>
+            <button @click="requestAccess" :disabled="accessRequested">{{ $t('club.requestAccess') }}</button>
         </div>
     </div>
 
@@ -80,7 +83,8 @@ export default {
                 name: '',
             },
             openRequests: [],
-            accessAllowed: false
+            accessAllowed: false,
+            accessRequested: false
         }
     },
     methods: {
@@ -152,12 +156,19 @@ export default {
         }, 
         async requestAccess() {
             try {
+                if (this.accessRequested) return;
                 const clubId = this.getClubId();
                 const response = await apiClient.get(`/clubs/request/${clubId}`);
                 if (response.status === 200) {
+                    this.accessRequested = true;
                     await this.showInfo(this.$t('messages.info'), this.$t('club.accessRequested'), '', 'info');
                 }
             } catch (error) {
+                if (error?.response?.status === 409) {
+                    this.accessRequested = true;
+                    await this.showInfo(this.$t('messages.info'), this.$t('club.accessRequested'), '', 'info');
+                    return;
+                }
                 const message = safeErrorMessage(error, this.$t('club.accessRequestFailed'));
                 await this.showInfo(this.$t('messages.error'), message, '', 'error');
             }
@@ -230,4 +241,9 @@ ul {
 .gender-symbol.gender-unknown { color: #444; }
 .gender-symbol { margin-right: .35rem; opacity: .9; font-size: 1.05em; display: inline-block; width: 1.1em; text-align: center; }
 .is-test { font-style: italic; }
+.access-requested {
+    margin: 0.5rem 0;
+    color: #2e7d32;
+    font-weight: 600;
+}
 </style>