fix(web): resolve approval card race condition with polling

Race condition between polling (5s interval) and sign/reject operations
caused cards to flicker and reappear after being approved.

Fix:
- Pause polling during sign/reject API calls
- Resume polling after 1 second delay to allow backend state sync
- Apply same pattern to both signApproval and rejectApproval

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

apps/web/src/stores/approval.store.ts

@@ -176,6 +176,14 @@ export const useApprovalStore = create<ApprovalState>()(
     // Sign Approval
     // ==========================================================================
     signApproval: async (id, signerId, signerName, comment) => {
+      // 🔧 Race Condition 修復: 簽核期間暫停 Polling
+      const wasPolling = pollingTimer !== null
+      if (wasPolling) {
+        clearInterval(pollingTimer!)
+        pollingTimer = null
+        console.log('[Approval] Polling paused during sign')
+      }
+
       set({ signingId: id, error: null })
 
       try {
@@ -219,6 +227,14 @@ export const useApprovalStore = create<ApprovalState>()(
           }
         })
 
+        // 🔧 Race Condition 修復: 延遲 1 秒後恢復 Polling，讓後端有時間更新
+        if (wasPolling) {
+          setTimeout(() => {
+            get().startPolling(get().pollingInterval || DEFAULT_POLLING_INTERVAL)
+            console.log('[Approval] Polling resumed after sign')
+          }, 1000)
+        }
+
         return result
       } catch (err) {
         console.error('[Approval] Sign failed:', err)
@@ -226,6 +242,13 @@ export const useApprovalStore = create<ApprovalState>()(
           signingId: null,
           error: `Sign failed: ${err}`,
         })
+
+        // 🔧 失敗也要恢復 Polling
+        if (wasPolling) {
+          get().startPolling(get().pollingInterval || DEFAULT_POLLING_INTERVAL)
+          console.log('[Approval] Polling resumed after sign error')
+        }
+
         return null
       }
     },
@@ -234,6 +257,14 @@ export const useApprovalStore = create<ApprovalState>()(
     // Reject Approval
     // ==========================================================================
     rejectApproval: async (id, rejectorId, rejectorName, reason) => {
+      // 🔧 Race Condition 修復: 拒絕期間暫停 Polling
+      const wasPolling = pollingTimer !== null
+      if (wasPolling) {
+        clearInterval(pollingTimer!)
+        pollingTimer = null
+        console.log('[Approval] Polling paused during reject')
+      }
+
       set({ rejectingId: id, error: null })
 
       try {
@@ -266,6 +297,14 @@ export const useApprovalStore = create<ApprovalState>()(
           }
         })
 
+        // 🔧 Race Condition 修復: 延遲 1 秒後恢復 Polling
+        if (wasPolling) {
+          setTimeout(() => {
+            get().startPolling(get().pollingInterval || DEFAULT_POLLING_INTERVAL)
+            console.log('[Approval] Polling resumed after reject')
+          }, 1000)
+        }
+
         return true
       } catch (err) {
         console.error('[Approval] Reject failed:', err)
@@ -273,6 +312,13 @@ export const useApprovalStore = create<ApprovalState>()(
           rejectingId: null,
           error: `Reject failed: ${err}`,
         })
+
+        // 🔧 失敗也要恢復 Polling
+        if (wasPolling) {
+          get().startPolling(get().pollingInterval || DEFAULT_POLLING_INTERVAL)
+          console.log('[Approval] Polling resumed after reject error')
+        }
+
         return false
       }
     },