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/components/step-library/StepLibraryBrowser.tsx

@@ -1,6 +1,8 @@
 import { useState, useEffect, useMemo } from 'react'
 import { Search, ChevronDown, ChevronUp, Loader2 } from 'lucide-react'
 import { Button } from '@/components/ui/Button'
+import { EmptyState } from '@/components/common/EmptyState'
+import { StepLibraryIllustration } from '@/components/common/EmptyStateIllustrations'
 import { cn } from '@/lib/utils'
 import { stepsApi } from '@/api/steps'
 import { stepCategoriesApi } from '@/api/stepCategories'
@@ -259,12 +261,24 @@ export function StepLibraryBrowser({ onInsert, onCreateNew, showCreateButton = f
             </Button>
           </div>
         ) : steps.length === 0 ? (
-          <div className="rounded-lg border border-border bg-accent/50 p-12 text-center">
-            <p className="mb-2 text-lg font-medium text-foreground">No steps found</p>
-            <p className="text-sm text-muted-foreground">
-              {hasActiveFilters ? 'Try adjusting your filters' : 'Create your first step to get started!'}
-            </p>
-          </div>
+          hasActiveFilters ? (
+            <div className="rounded-lg border border-border bg-accent/50 p-12 text-center">
+              <p className="mb-2 text-lg font-medium text-foreground">No steps found</p>
+              <p className="text-sm text-muted-foreground">Try adjusting your filters</p>
+            </div>
+          ) : (
+            <EmptyState
+              illustration={<StepLibraryIllustration />}
+              title="Build a reusable step library"
+              description="Save common troubleshooting steps once, reuse them across flows. Keeps your team consistent and saves build time."
+              action={
+                onCreateNew ? (
+                  <Button onClick={onCreateNew}>Browse Steps</Button>
+                ) : undefined
+              }
+              learnMoreLink="/guides/step-library"
+            />
+          )
         ) : (
           <div className="space-y-6">
             {/* My Steps */}