Remove archived design spec after split into numbered docs

The original design spec content lives entirely in the numbered
harness docs; the file itself is recoverable from the initial commit.
Drop it from agent-context routes and fix all doc references.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

docs/01-vision.md

@@ -45,4 +45,4 @@ soft_quay_web 要解决:SoftBox 软件发布者(自己)发布自家系列软件
 - 不生成未测试目标的占位包。
 - 不定义第二套包级验签域——外层清单 Ed25519 签名已覆盖 package 的 `url/size/sha256/signature` 文本。
 
-> MVP 的具体功能范围与验收标准,见 [需求](02-requirements.md);原始设计规格见 [softbox-catalog-design.md](softbox-catalog-design.md)。
+> MVP 的具体功能范围与验收标准,见 [需求](02-requirements.md)。