feat: UX enhancements, member limits, forecast fix, and menu cleanup (v2026.3.19)

- Onboarding wizard: add Reserve Account step between Operating and Assessments,
  redirect to Budget Planning on completion
- Dashboard: health score pending state shows clickable links to set up missing items
- Projects/Vendors: rich empty-state wizard screens with real-world examples and CTAs
- Investment Planning: auto-refresh AI recommendations when empty or stale (>30 days)
- Hide Invoices and Payments menus (see PARKING-LOT.md for re-enablement)
- Send welcome email via Resend when new members are added to a tenant
- Enforce 5-member limit for Starter/Standard/Professional plans (Enterprise unlimited)
- Cash flow forecast: only mark months as "Actual" when journal entries exist,
  fixing the issue where months without data showed as actuals
- Bump version to 2026.3.19

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

frontend/src/stores/authStore.ts

@@ -6,6 +6,7 @@ interface Organization {
   name: string;
   role: string;
   status?: string;
+  planLevel?: string;
   settings?: Record<string, any>;
 }