Refactor UI auth flow, remove uploads app files

Rework client UI state: move and update showLogin/showApp in public/app.js to explicitly set display styles when toggling screens and ensure user info and file load on app show. Remove the theme toggle from public/index.html and simplify CSS by collapsing color variable definitions (dark-theme-focused) in public/style.css. Add a VS Code workspace file. Remove the old uploads/Think app (Dockerfile, package.json, server.js and associated lockfile).

FTP-Server.code-workspace

@@ -0,0 +1,8 @@
+{
+	"folders": [
+		{
+			"path": "."
+		}
+	],
+	"settings": {}
+}