feat(api): public photo feed with stable cursor pagination

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

services/api/src/public/public.controller.ts

@@ -16,10 +16,12 @@ import {
 } from '@nestjs/common';
 import { ErrorCodes } from '@photo/contracts';
 import { ApiException } from '../api-exception';
+import { parseCursor } from '../albums/albums.controller';
 import {
   DEFAULT_PUBLIC_PHOTO_PAGE_SIZE,
   MAX_PUBLIC_PHOTO_PAGE_SIZE,
   type PublicAlbumResponse,
+  type PublicPhotoListResponse,
   PublicService,
 } from './public.service';
 
@@ -58,4 +60,24 @@ export class PublicController {
   ): Promise<PublicAlbumResponse> {
     return this.publicService.getPublicAlbum(token, locale);
   }
+
+  /**
+   * 公开照片列表：仅 published；(publishedAt,id) 稳定倒序键集游标；category
+   * 限本册分类；locale 不校验取值（非法值静默回退语义，Task 5 决策）。
+   */
+  @Get(':token/photos')
+  listPublicPhotos(
+    @Param('token') token: string,
+    @Query('category') category: string | undefined,
+    @Query('locale') locale: string | undefined,
+    @Query('cursor') cursor: string | undefined,
+    @Query('limit') limit: string | undefined,
+  ): Promise<PublicPhotoListResponse> {
+    return this.publicService.listPublicPhotos(token, {
+      category,
+      // locale 仅保证「不因非法值报 400」，列表无语言敏感字段，不向下传。
+      cursor: parseCursor(cursor),
+      limit: parsePublicPhotoLimit(limit),
+    });
+  }
 }