Fix UI visibility, form CSS, and quick-connect modal

- Fix drawer/modal backdrop class names and is-visible transitions
- Add protocol tab, settings tab, and command palette CSS
- Add form-section-content as CSS alias for form-section-body
- Add missing form CSS: form-hint, form-toggle, jump-host-row, preset-row
- Add btn-outline, form-input-sm, form-select-sm styles
- Replace window.prompt() with custom modal for WKWebView compatibility
- Remove diagnostic banner and instrumentation

frontend/src/css/components.css

@@ -132,6 +132,18 @@
 .btn-group {
     display: inline-flex;
 }
+
+/* Outline button — transparent background, subtle border */
+.btn-outline {
+    background: transparent;
+    border: 1px solid var(--border);
+    color: var(--text-secondary);
+}
+.btn-outline:hover {
+    background: var(--surface-2);
+    color: var(--text-primary);
+}
+
 .btn-group .btn {
     border-radius: 0;
 }