feat(routing): switch from hash routing to HTML5 History API

Remove all window.location.hash assignments and hashchange events.
Navigate with history.pushState; listen on popstate. Fix base href to
'/' so assets resolve correctly on deep paths. Update magic link URL.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/services/backend.ts

@@ -76,7 +76,7 @@ export const HybridBackend = {
     localStorage.removeItem('SCOREODONTO_USER_DATA');
     localStorage.removeItem('SCOREODONTO_WORKSPACES');
     localStorage.removeItem('SCOREODONTO_ACTIVE_WORKSPACE');
-    window.location.hash = '/';
+    window.location.href = '/';
     window.location.reload();
   },