Add SMS gating, TCPA terms agreement, and compose-before-send modal

- Three-tier SMS gate: platform kill-switch → admin force-disable → plan AllowSms → company opt-in
- CompanySmsAgreement entity records admin acceptance of TCPA terms with IP, user agent, and terms version
- SMS terms of service modal on Company Settings with versioned re-agreement (AppConstants.SmsTermsVersion)
- Dev redirect: non-production SMS routed to Twilio:DevRedirectPhone to protect real customer numbers
- Removed redundant Ready for Pickup SMS (Job Completed covers it)
- Role-based compose modal on job completion: Admin/Manager reviews and edits before send; ShopFloor auto-sends
- Send SMS button on job details for ad-hoc messages (Admin/Manager only)
- SendJobSmsAsync auto-appends STOP opt-out language if missing
- Migrations: AddSmsGating, AddCompanySmsAgreement

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

src/PowderCoating.Web/Views/PlatformSubscription/Index.cshtml

@@ -169,6 +169,19 @@
                                     }
                                 </td>
                             </tr>
+                            <tr>
+                                <td class="text-muted">SMS Notifications</td>
+                                <td>
+                                    @if (plan.AllowSms)
+                                    {
+                                        <span class="badge bg-success">Enabled</span>
+                                    }
+                                    else
+                                    {
+                                        <span class="badge bg-secondary">Disabled</span>
+                                    }
+                                </td>
+                            </tr>
                             <tr class="table-light">
                                 <td colspan="2" class="fw-semibold small text-uppercase text-muted py-1">Stripe</td>
                             </tr>