refactor: archive GUI clients; keep minimal TUI with hooks/API

Move Qt/Tauri/full Web SPA under archive/, ship hermit as CLI/TUI plus
libcstcore and cst-webui/1 HTTP+SSE (turn lifecycle hooks, capabilities).

Co-authored-by: Cursor <cursoragent@cursor.com>

archive/qt-app/icons/arrow-down.svg

@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="24" height="24">
+  <defs id="defs3051">
+    <style type="text/css" id="current-color-scheme">.ColorScheme-Text { color: #fcfcfc; } </style>
+  </defs>
+  <g transform="translate(1,1)">
+    <path style="fill:currentColor;fill-opacity:1;stroke:none" d="m3.707031 7l-.707031.707031 6.125 6.125 1.875 1.875 1.875-1.875 6.125-6.125-.707031-.707031-6.125 6.125-1.167969 1.167969-1.167969-1.167969-6.125-6.125" class="ColorScheme-Text"/>
+  </g>
+</svg>