Auto-detect single vs multi-zone center from AFP during provisioning

[rchlfryn]

Summary

When provisioning a new avalanche center, we should automatically check the AFP (Avalanche Forecast Program) data to determine if the center is a single-zone or multi-zone operation and provision accordingly.

Currently, provisioning creates the same 7 built-in pages regardless of zone count. Zone-aware navigation is handled dynamically at runtime (src/components/Header/utils.ts), but the built-in pages created during provisioning should also differ.

Areas to update

• src/collections/Tenants/endpoints/provisionTenant.ts — Query AFP via getActiveForecastZones() from src/services/nac/nac.ts to determine zone count, then create the appropriate built-in pages:
  • Single zone: Create /forecasts/avalanche/{zone} page
  • Multi-zone: Create /forecasts/avalanche (all forecasts) + one page per zone at /forecasts/avalanche/{zone}
• docs/onboarding.md — Already documents the single vs multi-zone difference (lines 22-34), update if provisioning handles this automatically
• Filter built-in pages using DVAC navigation — extractNavReferences (in provisionTenant.ts) already extracts builtInPageUrls from the template navigation. Use this to filter BUILT_IN_PAGES so only navigation-referenced built-in pages are created, matching how pages are already filtered. See TODO comments in provisionTenant.ts and onboardingActions.ts referencing Make automated topLevelNavItems use built-in pages & nav improvements #1002.

Context

From the onboarding provisioning PR — zone configuration was identified as something that could be automated rather than manually configured. The NAC API already provides zone data via getActiveForecastZones(centerSlug).

Acceptance Criteria

• Query AFP data during provisioning to determine zone count
• Create zone-specific built-in pages based on single vs multi-zone
• Filter built-in pages to those referenced in DVAC's navigation (use navBuiltInPageUrls from extractNavReferences)
• Handle cases where AFP data is unavailable (fall back to manual configuration)
• Update onboarding docs to reflect automation

[rchlfryn]

The seed script on the nav-updates branch implements the same zone-detection logic and can serve as a reference for this work:

• src/endpoints/seed/index.ts — calls getActiveForecastZones() per tenant, then creates zone-specific built-in pages (single zone: /forecasts/avalanche/{slug}; multi-zone: /forecasts/avalanche + per-zone pages)
• src/endpoints/seed/navigation.ts — populates the forecasts nav entry differently based on zone count, with zones sorted by rank

provisionTenant.ts should follow the same pattern.