重构: P0前端架构(useAiSend/useAiEvents/useToolCard拆分+status union全)

squash合并:
- P0-1 useAiSend审批抽离(useAiApproval)
- P0-2 useAiEvents switch拆3域handler
- P0-3 useToolCard formatToolResult策略表
- P0-4 status union(Idea+Task+Project+Workflow+AiToolCall)

src/stores/ai.ts

@@ -51,6 +51,7 @@ const PARTS_SIZE_BUDGET = 50 * 1024 * 1024 // 50MB(base64 char 计)
 import { useAiEvents } from '@/composables/ai/useAiEvents'
 import { useAiStream } from '@/composables/ai/useAiStream'
 import { useAiSend, initDrainQueueListener } from '@/composables/ai/useAiSend'
+import { useAiApproval } from '@/composables/ai/useAiApproval'
 import { useAiConversations } from '@/composables/ai/useAiConversations'
 import { useAiWindow } from '@/composables/ai/useAiWindow'
 import { useAiPanel } from '@/composables/ai/useAiPanel'
@@ -199,6 +200,7 @@ export function useAiStore() {
     ...useAiEvents(),
     ...useAiStream(),
     ...useAiSend(),
+    ...useAiApproval(),
     ...useAiConversations(),
     ...useAiWindow(),
     ...useAiPanel(),