fix(theme): payload 契约上提 contracts；空路由明错；ui.routeHrefFor；eslint astro ignore

审查修复（Plan 4 Task 3 review）：
- 载荷类型单一事实来源：ContentEntry/TaxonomyEntry/TaxonomyTerm/RouteEntry/
  AssetEntry/RenderManifestMeta/SiteConfigPayload/BrandConfigPayload 上提
  @sf/contracts/render-snapshot（纯新增、不动既有导出——冻结面加法无需升版）；
  物化端（apps/api build/render-snapshot.ts）与主题 load-render-data 同源引用，
  双份手写镜像漂移即编译期破裂；主题侧 re-export 保持既有 import 面
- loader 空路由表前置明错（正常发布站点至少含首页路由——静默渲染会产零页站点）
- ui.routeHrefFor：targetContentId → 纯路径 html 落点（redirect/查询行不参与，
  无落点 undefined 不虚构——Task 4 分派器入口）+ 测试
- 具夹 assets.json copyPath 去机器相关绝对路径（改仓库相对）
- eslint ignores 增 **/.astro/**（astro build 再生目录）

354 根测试 + 18 主题测试全绿；五段 typecheck；lint（.astro 存在态验证后清理）。

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

themes/pilot-minimal/test/fixtures/render-input/assets.json

@@ -1 +1 @@
-[{"altText":null,"byteSize":1234,"copyPath":"D:/project/cms-one/storage/snapshots/media_bundle/2026/10/fixture-a.png","detectedMimeType":"image/png","height":80,"publicPath":"/wp-content/uploads/2026/10/fixture-a.png","sha256":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","storagePath":"snapshots/media_bundle/2026/10/fixture-a.png","width":100}]
+[{"altText":null,"byteSize":1234,"copyPath":"storage/snapshots/media_bundle/2026/10/fixture-a.png","detectedMimeType":"image/png","height":80,"publicPath":"/wp-content/uploads/2026/10/fixture-a.png","sha256":"aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa","storagePath":"snapshots/media_bundle/2026/10/fixture-a.png","width":100}]