Add Customer Intake Kiosk help article and knowledge base entry

- New Help article at /Help/CustomerIntakeKiosk covering setup, in-person
  and remote intake flows, what happens on submission, reviewing intakes,
  and troubleshooting (signature pad, connection issues, seed data)
- Add kiosk entry to _HelpNav under Operations
- Update HelpKnowledgeBase: nav overview, full kiosk section, two new
  common workflow entries (walk-in kiosk and remote intake)

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

src/PowderCoating.Web/Views/Help/_HelpNav.cshtml

@@ -25,6 +25,10 @@
                asp-controller="Help" asp-action="Jobs">
                 <i class="bi bi-briefcase"></i> Jobs
             </a>
+            <a class="nav-link py-2 px-3 d-flex align-items-center gap-2 @(currentAction == "CustomerIntakeKiosk" ? "active fw-semibold text-primary" : "text-body")"
+               asp-controller="Help" asp-action="CustomerIntakeKiosk">
+                <i class="bi bi-tablet"></i> Customer Intake Kiosk
+            </a>
             <a class="nav-link py-2 px-3 d-flex align-items-center gap-2 @(currentAction == "Quotes" ? "active fw-semibold text-primary" : "text-body")"
                asp-controller="Help" asp-action="Quotes">
                 <i class="bi bi-file-earmark-text"></i> Quotes