feat: roll out illustrative empty states across 8 pages with 2 new guide entries

- TreeLibraryPage: split empty state into no-flows (illustration + CTA) vs no-filter-results
- MyAnalyticsPage/TeamAnalyticsPage: add zero-sessions empty state with illustration
- SessionHistoryPage: split into no-sessions (illustration) vs no-filter-results
- StepLibraryBrowser: illustrative empty state when no steps exist
- ScriptTemplateList: replace plain empty state with ScriptIllustration
- MySharesPage: replace icon-based empty state with ShareIllustration
- IntegrationsPage: add IntegrationIllustration above setup form
- Add script-templates and psa-setup guides to guides data
- Add EmptyState vitest tests (7 tests)

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

frontend/src/pages/TreeLibraryPage.tsx

@@ -3,6 +3,7 @@ import { useNavigate, useSearchParams } from 'react-router-dom'
 import { X, RotateCcw, Play, FileUp } from 'lucide-react'
 import { PageMeta } from '@/components/common/PageMeta'
 import { Button } from '@/components/ui/Button'
+import { FlowIllustration } from '@/components/common/EmptyStateIllustrations'
 import { treesApi } from '@/api/trees'
 import { categoriesApi } from '@/api/categories'
 import { foldersApi } from '@/api/folders'
@@ -496,14 +497,29 @@ export function TreeLibraryPage() {
               <Spinner />
             </div>
           ) : trees.length === 0 ? (
-            <EmptyState
-              title="No flows found"
-              description={
-                (searchQuery || hasActiveFilters)
-                  ? 'Try adjusting your filters.'
-                  : 'Create your first flow to get started.'
-              }
-            />
+            (searchQuery || hasActiveFilters) ? (
+              <EmptyState
+                title="No flows match your filters"
+                description="Try adjusting your search or filters."
+                action={
+                  <Button variant="secondary" onClick={clearAllFilters}>
+                    Clear Filters
+                  </Button>
+                }
+              />
+            ) : (
+              <EmptyState
+                illustration={<FlowIllustration />}
+                title="Build your first troubleshooting flow"
+                description="Flows guide your team through proven resolution paths, capturing every decision along the way."
+                action={
+                  canCreateTrees ? (
+                    <CreateFlowDropdown aiEnabled={aiEnabled} label="Create a Flow" />
+                  ) : undefined
+                }
+                learnMoreLink="/guides/creating-flows"
+              />
+            )
           ) : (
             <>
               {treeLibraryView === 'grid' && (