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/sessionTitle.ts

@@ -37,8 +37,8 @@ export function extractConversationText(messages: Message[]): string {
     if ('isMeta' in msg && msg.isMeta) continue
     if (
       'origin' in msg &&
-      (msg as any).origin &&
-      (msg as any).origin.kind !== 'human'
+      (msg as unknown as { origin?: { kind?: string } }).origin &&
+      (msg as unknown as { origin: { kind?: string } }).origin.kind !== 'human'
     )
       continue
     const content = msg.message!.content
@@ -116,7 +116,9 @@ export async function generateSessionTitle(
       },
     })
 
-    const text = extractTextContent(result.message.content as any)
+    const text = extractTextContent(
+      result.message.content as readonly { readonly type: string }[],
+    )
 
     const parsed = titleSchema().safeParse(safeParseJSON(text))
     const title = parsed.success ? parsed.data.title.trim() || null : null