Use nullish coalescing operator (S6606) and fix duplicate id (S7930)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/components/AppHeader.vue

@@ -8,28 +8,28 @@
         class="flex justify-between items-center relative"
         v-show="showMember"
       >
-        <img
+        <span id="acct_mgmt_button">
-          id="acct_mgmt_button"
+          <img
-          v-if="!isHeadHovered"
+            v-if="!isHeadHovered"
-          src="@/assets/icon-head-black.svg"
+            src="@/assets/icon-head-black.svg"
-          @mouseenter="isHeadHovered = true"
+            @mouseenter="isHeadHovered = true"
-          width="32"
+            width="32"
-          height="32"
+            height="32"
-          @click="toggleIsAcctMenuOpen"
+            @click="toggleIsAcctMenuOpen"
-          class="cursor-pointer z-50"
+            class="cursor-pointer z-50"
+            alt="user-head"
+          />
+          <img
+            v-else
+            src="@/assets/icon-head-blue.svg"
+            @mouseleave="isHeadHovered = false"
+            width="32"
+            height="32"
+            @click="toggleIsAcctMenuOpen"
+            class="cursor-pointer z-50"
           alt="user-head"
-        />
+          />
-        <img
+        </span>
-          id="acct_mgmt_button"
-          v-else
-          src="@/assets/icon-head-blue.svg"
-          @mouseleave="isHeadHovered = false"
-          width="32"
-          height="32"
-          @click="toggleIsAcctMenuOpen"
-          class="cursor-pointer z-50"
-          alt="user-head"
-        />
       </div>
     </div>
   </div>

src/stores/acctMgmt.ts

@@ -184,7 +184,7 @@ export const useAcctMgmtStore = defineStore('acctMgmtStore', {
 
       try {
         const response = await apiClient.put(apiEdit, {
-          username: editDetail.newUsername != null ? editDetail.newUsername : editDetail.username,
+          username: editDetail.newUsername ?? editDetail.username,
           password: editDetail.password,
           name: editDetail.name,
           is_active: editDetail.is_active,