Add NWAC weather station data pages

[rchlfryn]

Description

Adds native weather-station data pages to AvyWeb for NWAC, recreating the nwac.us /weatherdata/<station>/now/ tables (currently a WordPress plugin). Data-first React tables backed by SnowObs, fetched server-side so the API token never reaches the browser.

Related Issues

Part of #1106

Key Changes

• SnowObs service (src/services/snowobs): server-side wx/v1/station/data/timeseries fetch (token via SNOWOBS_TOKEN env), zod-validated response, and a pure transform → render-ready tables — cumulative precip, cross-station full-outer-join on timestamp, UTC→America/Vancouver, short sensor/unit labels. Unit-tested.
• Station registry (src/constants/weatherStations.ts): 32 station groups ported from the legacy station_group_tables_config — slug, legacySlug (for future redirects), region, stids, columns. Integrity-tested.
• Detail route /weather/stations/[station]: ISR (10-min revalidate), 24h / 7-day range toggle, latest-observation timestamp + stale flag (>2h), per-station error isolation, notFound() for centers without the stations platform.
• Index /weather/stations: region-grouped directory (up to 4 columns) + station picker.
• StationNowTable: shadcn table — zebra rows, sticky time column, tightened/centered columns, stacked label/unit/elevation headers.
• NWAC-only "Weather Data" nav item in the Weather dropdown (seed + provisioning + migration).

How to test

• pnpm dev, then load nwac.localhost:3000/weather/stations and /weather/stations/hurricane-ridge.
• Toggle Last 24 Hours / Last 7 Days; spot-check values against nwac.us.
• Confirm other centers (dvac/sac/snfac) 404 on these routes.
• pnpm test — covers the SnowObs transform and the registry.

Screenshots / Demo video

Kapture.2026-07-10.at.10.06.26.mp4

Migration Explanation

None needed - can add page via Built In Pages

Future enhancements / Questions

• SnowObs token: currently read from env with a public fallback token committed (the same one nwac.us already serves in client HTML). Consider dropping the fallback and requiring the env var to keep secret scanners happy.
• Region "area" pages with historical date-range browsing (prototyped separately, deferred).
• Data Portal graphs (legacy D3 → React charts).
• nwac.us cutover: redirects from /weatherdata/<slug>/now/ → new URLs (deferred; legacySlug is stored for this).

🤖 Generated with Claude Code

[github-actions]

Preview deployment: https://featxweather-station-tables.preview.avy-fx.org