Update staff roles, documentation, and add tenant API

Staff Roles:
- Remove Support Staff default role (now Manager and Staff only)
- Add position field for custom role ordering
- Update StaffRolesSettings with improved permission UI
- Add RolePermissions component for visual permission display

Documentation Updates:
- HelpStaff: Explain two-tier permission system (User Roles + Staff Roles)
- HelpSettingsStaffRoles: Update default roles, add settings access permissions
- HelpComprehensive: Update staff roles section with correct role structure
- HelpCustomers: Add customer creation and onboarding sections
- HelpContracts: Add lifecycle, snapshotting, and signing experience docs
- HelpSettingsAppearance: Update with 20 color palettes and navigation text

Tenant API:
- Add new isolated API at /tenant-api/v1/ for third-party integrations
- Token-based authentication with scope permissions
- Endpoints: business, services, resources, availability, bookings, customers, webhooks

Tests:
- Add test coverage for Celery tasks across modules
- Reorganize schedule view tests for better maintainability

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontend/src/i18n/locales/en.json

@@ -248,6 +248,17 @@
       "retrieveCustomer": "Retrieve a customer",
       "updateCustomer": "Update a customer",
       "listCustomers": "List all customers",
+      "filtering": "Filtering & Sorting",
+      "filteringDescription": "Most list endpoints support filtering and sorting to help you retrieve exactly the data you need. Use query parameters to narrow your results.",
+      "comparisonOperators": "Comparison Operators",
+      "comparisonOperatorsDescription": "Append these suffixes to field names to filter by comparison:",
+      "servicesFilters": "Services Filters",
+      "bookingsFilters": "Bookings Filters",
+      "sorting": "Sorting",
+      "sortingDescription": "Use the ordering parameter to sort results. Prefix with a minus sign (-) for descending order.",
+      "filterServicesExample": "Filter Services Example",
+      "filterBookingsExample": "Filter Bookings Example",
+      "filteredResponse": "Filtered Response",
       "webhooks": "Webhooks",
       "webhookEvents": "Webhook events",
       "webhookEventsDescription": "Webhooks allow you to receive real-time notifications when events occur in your business.",
@@ -3777,7 +3788,15 @@
       "emailTemplates": "Email Templates",
       "embedWidget": "Embed Widget",
       "staffRoles": "Staff Roles",
-      "smsCalling": "SMS & Calling"
+      "smsCalling": "SMS & Calling",
+      "settingsSections": {
+        "business": "Business",
+        "branding": "Branding",
+        "integrations": "Integrations",
+        "access": "Access",
+        "communication": "Communication",
+        "billing": "Billing"
+      }
     },
     "introduction": {
       "title": "Introduction",