feat: K2/밀링 앱을 NPM 서브도메인(HTTPS)으로 전환, 홈 드롭다운 재추가

print.applecherry.net(K2 콤보 Fluidd) · mill.applecherry.net(CNC 밀링
OctoPrint)로 NPM 프록시+Let's Encrypt 설정 완료. 앱들이 이제 HTTPS라
mixed content 경고 없이 홈 드롭다운에 다시 노출.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PppKcQmeTJDQCpfcgKietu

web-ui/html/k2-app.html

@@ -38,7 +38,7 @@ body{background:var(--bg);color:var(--text);font-family:system-ui,sans-serif;dis
   <span class="hdr-sp"></span>
   <button class="hdr-btn" onclick="reconnectCam()">📷 카메라 재연결</button>
   <button class="hdr-btn" onclick="reloadFrame()">↺ 새로고침</button>
-  <a class="hdr-btn" href="http://192.168.0.114:4408/" target="_blank">↗ 새 탭</a>
+  <a class="hdr-btn" href="https://print.applecherry.net/" target="_blank">↗ 새 탭</a>
   <button class="hdr-btn" onclick="toggleTheme()">🌙</button>
 </header>
 
@@ -48,10 +48,10 @@ body{background:var(--bg);color:var(--text);font-family:system-ui,sans-serif;dis
     <span class="cam-status" id="cam-status">연결 중...</span>
   </div>
   <div class="frame-wrap">
-    <iframe id="k2-frame" src="http://192.168.0.114:4408/" title="Fluidd"></iframe>
+    <iframe id="k2-frame" src="https://print.applecherry.net/" title="Fluidd"></iframe>
     <div class="err" id="k2-err">
-      <div>Fluidd를 불러오지 못했습니다 (K2 콤보, 192.168.0.114:4408).</div>
-      <div><a href="http://192.168.0.114:4408/" target="_blank">새 탭에서 직접 열기 ↗</a></div>
+      <div>Fluidd를 불러오지 못했습니다 (print.applecherry.net).</div>
+      <div><a href="https://print.applecherry.net/" target="_blank">새 탭에서 직접 열기 ↗</a></div>
     </div>
   </div>
 </div>