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/linux/cst-agent-app.desktop

@@ -0,0 +1,15 @@
+[Desktop Entry]
+Type=Application
+Name=CST-agent
+GenericName=Local coding agent
+Comment=The engine in a window: workspace is the directory it is started in
+Exec=cst-agent-app
+TryExec=cst-agent-app
+Icon=cst-agent-app
+Terminal=false
+StartupNotify=true
+# Qt puts the application name in the Wayland app_id / WM_CLASS, so this has to
+# stay the file's own name or the launcher draws a generic icon.
+StartupWMClass=cst-agent-app
+Categories=Development;Utility;
+Keywords=agent;ai;assistant;code;

archive/qt-app/linux/cst-agent-app.svg

@@ -0,0 +1,12 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- The launcher icon: the prompt the CLI shows, on a tile in the window's own
+     palette (app/qml/Theme.qml). Installed under hicolor/scalable, so the
+     desktops that want raster sizes render it themselves. -->
+<svg xmlns="http://www.w3.org/2000/svg" width="128" height="128" viewBox="0 0 128 128">
+  <rect x="6" y="6" width="116" height="116" rx="26" ry="26"
+        fill="#15181a" stroke="#343b41" stroke-width="5"/>
+  <path d="M36 42 L56 64 L36 86" fill="none" stroke="#3daee9" stroke-width="12"
+        stroke-linecap="round" stroke-linejoin="round"/>
+  <path d="M69 88 H94" fill="none" stroke="#eff0f1" stroke-width="12"
+        stroke-linecap="round"/>
+</svg>