refactor(canvas): 替换自定义ID生成函数为nanoid并优化配置逻辑

- 移除自定义createId函数，统一使用nanoid库生成唯一标识符
- 将useEffectiveAiConfig Hook替换为resolveEffectiveConfig工具函数
- 直接从config store获取publicSettings避免额外的Hook依赖
- 更新所有组件中的ID生成调用以使用nanoid
- 简化buildApiUrl函数中的基础URL规范化逻辑

web/src/services/image-storage.ts

@@ -2,7 +2,7 @@
 
 import localforage from "localforage";
 
-import { createId } from "@/lib/id";
+import { nanoid } from "nanoid";
 import { readImageMeta } from "@/lib/image-utils";
 
 export type UploadedImage = {
@@ -19,7 +19,7 @@ const objectUrls = new Map<string, string>();
 
 export async function uploadImage(input: string | Blob): Promise<UploadedImage> {
   const blob = typeof input === "string" ? await (await fetch(input)).blob() : input;
-  const storageKey = `image:${createId()}`;
+  const storageKey = `image:${nanoid()}`;
   await store.setItem(storageKey, blob);
   const url = URL.createObjectURL(blob);
   objectUrls.set(storageKey, url);