fix(csp): remove all inline styles, scripts, and event handlers for strict CSP compliance

Replace ~50 inline style="" attributes with CSS classes, move 3 inline
<script> blocks to external JS files, replace all inline event handlers
(onclick, onerror) with addEventListener, and remove createElement('style')
from icons.js. All changes support the strict CSP policy (style-src 'self';
script-src 'self') without weakening it.

static/js/views/nextcloud/success.js

@@ -0,0 +1,7 @@
+document.getElementById('close-window-btn').addEventListener('click', function() {
+    window.close();
+});
+// Auto-close after 3 seconds
+setTimeout(function() {
+    window.close();
+}, 3000);