fix: toast visibility — opaque backgrounds and flash scope matching with query strings

Two bugs in the toast redesign:

1. Variant backgrounds (success/warning/info/error) used rgba with 12-20%
   opacity, making toasts semi-transparent over page content. Fixed by
   layering the tint over a solid background via linear-gradient compositing.

2. Flash messages with scoped paths including query strings (e.g.
   edit pages with ?return=...) were not matched by Flash::peek(Request::path())
   since path() strips the query. Added fallback to pathWithQuery() matching.

Also moved flash partial before JS init scripts to ensure DOM is present
when the component runtime mounts.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/js/components/app-flash-auto-dismiss.js

@@ -6,7 +6,7 @@ import { resolveHost } from '../core/app-dom.js';
 
 export function initFlashAutoDismiss(root = document, options = {}) {
   const {
-    selector = '.app-toast-stack .notice[data-flash-timeout]',
+    selector = '.notice[data-flash-timeout]',
     defaultTimeout = 0,
   } = options;
   const host = resolveHost(root);