Add SMS Agreements admin page and update help docs

- Add /SmsAgreements SuperAdmin page listing per-company SMS terms acceptance
  status, with stats cards, filter/search, and a full acceptance history modal
  (terms version, accepted by, timestamp, IP, user agent)
- Add SMS Agreements nav link under Tenants & Billing in the platform sidebar
- Update HelpKnowledgeBase and Help docs (Quotes, Settings) to document
  quote approval via SMS and the reuse of existing approval tokens

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

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

@@ -265,12 +265,13 @@
                 <i class="bi bi-send text-primary me-2"></i>Sending a Quote
             </h2>
             <p>
-                Once a quote is saved as a Draft and you are happy with the pricing and details, you can mark it
-                as sent to the customer.
+                Once a quote is saved as a Draft and you are happy with the pricing and details, you can send it
+                to the customer via email or SMS, or both.
             </p>
+            <h3 class="h6 fw-semibold mt-3 mb-2">Send via Email</h3>
             <ol class="mb-3">
                 <li class="mb-2">Open the quote from the Quotes list and go to its Details page.</li>
-                <li class="mb-2">Click <strong>Send Quote</strong>. The status changes from Draft to Sent.</li>
+                <li class="mb-2">Click <strong>Send Quote via Email</strong>. The status changes from Draft to Sent and a PDF is emailed to the customer with an approval link.</li>
                 <li class="mb-2">If email notifications are configured for your company, the customer will automatically receive an email with the quote details.</li>
             </ol>
             <div class="alert alert-permanent alert-warning d-flex gap-2 mb-3" role="alert">
@@ -283,9 +284,20 @@
                     under their contact settings.
                 </div>
             </div>
+            <h3 class="h6 fw-semibold mt-3 mb-2">Send via SMS</h3>
+            <p>
+                Click <strong>Send Quote via SMS</strong> on the Details page to text the customer a short message
+                containing their quote total and a link to the self-service approval portal. The customer can open the
+                link on their phone and approve or decline without logging in.
+            </p>
+            <ul class="mb-3">
+                <li class="mb-1">The customer must have <strong>SMS Opt-In</strong> enabled and a <strong>Mobile Phone</strong> number on their record.</li>
+                <li class="mb-1">If you already sent the quote via email, the same approval link is reused — both the email link and SMS link remain valid simultaneously.</li>
+                <li class="mb-1">For prospect quotes, the SMS goes to the <strong>Prospect Phone</strong> field on the quote.</li>
+            </ul>
             <p>
                 You can also manually mark a quote as <strong>Approved</strong> or <strong>Rejected</strong> when
-                you hear back from the customer verbally or by phone, without going through a formal email send.
+                you hear back from the customer verbally or by phone, without going through a formal email or SMS send.
                 Use the status buttons on the quote Details page to do this.
             </p>
             <div class="alert alert-permanent alert-secondary d-flex gap-2 mb-0" role="alert">