docs(ui): Add UI layout refactor plan and OpenSpec changes

- Update decision-log with UI layout decisions (Feb 18, 2026)
- Update architecture with frontend layout patterns
- Update config.yaml with TDD, documentation, UI standards rules
- Create p00-api-documentation change (Scribe annotations)
- Create p01-ui-foundation change (types, stores, Lucide)
- Create p02-app-layout change (AppLayout, Sidebar, TopBar)
- Create p03-dashboard-enhancement change (PageHeader, StatCard)
- Create p04-content-patterns change (DataTable, FilterBar)
- Create p05-page-migrations change (page migrations)
- Fix E2E auth tests (11/11 passing)
- Add JWT expiry validation to dashboard guard

frontend/src/lib/components/Auth/LoginForm.svelte

@@ -23,7 +23,7 @@
 
   type LoginFormData = z.infer<typeof loginSchema>;
 
-  // Form data - use $state for reactivity
+  // Form data
   let formData: LoginFormData = $state({
     email: '',
     password: '',
@@ -43,7 +43,9 @@
       if (err instanceof z.ZodError) {
         err.errors.forEach((error) => {
           const field = error.path[0] as keyof LoginFormData;
-          errors[field] = error.message;
+          if (!errors[field]) {
+            errors[field] = error.message;
+          }
         });
       }
       return false;
@@ -59,7 +61,7 @@
   }
 </script>
 
-<form class="space-y-4" onsubmit={handleSubmit}>
+<form class="space-y-4" onsubmit={handleSubmit} novalidate>
   {#if errorMessage}
     <div class="alert alert-error" role="alert">
       <svg