fix(ds-app): DSBaseURL.tailscale placeholder를 GPU canonical Tailscale IP로 정정

ds-gpu.tailnet-name.ts.net(실재하지 않는 placeholder) → http://100.110.63.63:8000/api.
contract/CONTRACT.md·CompositionTests 의 기존 값과 일치. DS 본체 = GPU 서버 유지
확정(2026-06-07)에 따른 앱 연결 타깃 정합. swift test 72 green.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

clients/ds-app/Sources/DSKit/DSConfig.swift

@@ -1,8 +1,8 @@
 import Foundation
 
-/// Injectable base URL. Public TLS by default; Tailscale alternative uses a MagicDNS hostname
-/// (NOT a hardcoded 100.x IP, which changes on node re-registration). Scaffold never makes a live
-/// call, so the Tailscale host is a placeholder until FU-A.
+/// Injectable base URL. Public TLS by default; Tailscale alternative = GPU 서버 canonical
+/// Tailscale IP (infra_inventory.md 단일 진실, 2026-06-07 사용자 확정 — DS 본체 = GPU 서버 유지,
+/// contract/CONTRACT.md·CompositionTests 와 동일 값).
 public enum DSBaseURL: Sendable {
     case publicTLS
     case tailscale
@@ -11,7 +11,7 @@ public enum DSBaseURL: Sendable {
     public var url: URL {
         switch self {
         case .publicTLS: return URL(string: "https://document.hyungi.net/api")!
-        case .tailscale: return URL(string: "http://ds-gpu.tailnet-name.ts.net:8000/api")!
+        case .tailscale: return URL(string: "http://100.110.63.63:8000/api")!
         case .custom(let u): return u
         }
     }