chore: 清理 src 下 33 项死代码和类型断言

删除未使用的文件/目录（mcp/adapter、cli/update.ts 等）、
未使用的重导出文件（design-system/color.ts 等 12 个）、
7 个零引用的导出函数、修复 5 处 as any 为精确类型。
净减少 ~1194 行代码，precheck 4077 测试全部通过。

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

src/utils/mcpInstructionsDelta.ts

@@ -65,8 +65,9 @@ export function getMcpInstructionsDelta(
     attachmentCount++
     if (msg.attachment!.type !== 'mcp_instructions_delta') continue
     midCount++
-    for (const n of (msg.attachment! as any).addedNames) announced.add(n)
-    for (const n of (msg.attachment! as any).removedNames) announced.delete(n)
+    const delta = msg.attachment! as unknown as McpInstructionsDelta
+    for (const n of delta.addedNames) announced.add(n)
+    for (const n of delta.removedNames) announced.delete(n)
   }
 
   const connected = mcpClients.filter(