feat: 电商页面 KeepAlive 保活机制，切换页面不再丢失生成状态

通过 display:none 模式实现轻量 KeepAlive，电商页面首次访问后保持挂载，
切换到其他页面再切回时所有右侧面板状态（上传图片、生成进度、结果）完整保留。
同时清理项目中的临时文件和本地冗余图片。

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

src/hooks/useGenerationStatus.ts

@@ -0,0 +1,41 @@
+import { useCallback, useRef, useState } from "react";
+
+export type GenStatus = "idle" | "ready" | "generating" | "done" | "failed";
+
+export interface UseGenerationStatusReturn {
+  status: GenStatus;
+  error: string | null;
+  abortRef: { current: boolean };
+  start: () => void;
+  succeed: () => void;
+  fail: (msg: string) => void;
+  reset: () => void;
+  cancel: () => void;
+  isGenerating: boolean;
+  isFailed: boolean;
+  isIdle: boolean;
+}
+
+export function useGenerationStatus(): UseGenerationStatusReturn {
+  const [status, setStatus] = useState<GenStatus>("idle");
+  const [error, setError] = useState<string | null>(null);
+  const abortRef = useRef({ current: false });
+
+  const start = useCallback(() => {
+    setStatus("generating");
+    setError(null);
+    abortRef.current = { current: false };
+  }, []);
+
+  const succeed = useCallback(() => setStatus("done"), []);
+  const fail = useCallback((msg: string) => { setStatus("failed"); setError(msg); }, []);
+  const reset = useCallback(() => { setStatus("idle"); setError(null); }, []);
+  const cancel = useCallback(() => { abortRef.current.current = true; }, []);
+
+  return {
+    status, error, abortRef, start, succeed, fail, reset, cancel,
+    isGenerating: status === "generating",
+    isFailed: status === "failed",
+    isIdle: status === "idle",
+  };
+}