feat(ui): add breadcrumb icons, fix alignment, and remove duplicate form headers

- add section icons to all breadcrumbs across every page
- fix breadcrumb nav display:flex so icons align vertically with buttons
- wrap all page breadcrumbs in pageToolbar div for consistent layout
- add Breadcrumbs to AllRunsPage which previously used a plain h1
- fix envCardHeader flex:1 so settings button hugs the right edge
- remove card header from environment create/edit forms (duplicated breadcrumb)

client/src/pages/scenario/EditStepPage.tsx

@@ -1,6 +1,7 @@
 import { useEffect, useState } from 'react';
 import { useNavigate, useParams } from 'react-router-dom';
 import { useTranslation } from 'react-i18next';
+import { X, Save, ClipboardList } from 'lucide-react';
 import { scenarios, steps } from '../../api';
 import type { Scenario, ScenarioStep } from '../../api';
 import { Breadcrumbs, Button, Card, Input, CodeEditor } from '../../ui';
@@ -57,7 +58,7 @@ export function EditStepPage() {
       <div className={styles.pageToolbar}>
         <Breadcrumbs
           items={[
-            { label: t('scenarios.title'), onClick: () => navigate('/scenarios') },
+            { label: t('scenarios.title'), icon: <ClipboardList size={14} />, onClick: () => navigate('/scenarios') },
             {
               label: scenario?.name ?? `#${id}`,
               onClick: () => navigate(`/scenarios/${id}`),
@@ -96,9 +97,11 @@ export function EditStepPage() {
                 variant="secondary"
                 onClick={() => navigate(`/scenarios/${id}`)}
               >
+                <X size={14} />
                 {t('steps.action_cancel')}
               </Button>
               <Button type="submit" loading={saving}>
+                <Save size={14} />
                 {t('steps.action_update')}
               </Button>
             </div>