docs(tempest): thicken weather station skill against current API research

Full skill-builder rebuild of tempest per issue #407:

- references/: four dense files replacing the single layouts crib sheet -
  rest-api-and-auth.md (personal-use token via tempestwx.com Settings ->
  Data Authorizations, token-as-query-parameter auth, StationSet wrapper,
  device_type HB/AR/SK/ST enum, observation parameters day_offset vs
  time_start/time_end, better_forecast unit-selection, error signatures),
  udp-broadcast-protocol.md (port 50222 listen-only broadcast, dispatch-
  by-type rule, obs_st 18-position UDP record, rapid_wind ob, evt_precip/
  evt_strike, hub_status/device_status named fields), observation-layouts-
  and-units.md (REST 22-position obs_st vs UDP 18, obs_air 8, obs_sky 17
  vs 14, daily obs_*_ext summaries, metric-native unit tables), and cli-
  worked-recipes.md (six executable pipelines). Every file ends with a
  Sources footer citing live-verified official docs (apidocs.tempestwx.com,
  weatherflow.github.io/Tempest).
- scripts/tempest: fixed researched bugs - rapid_wind handler iterated the
  single ob array element-wise (TypeError on real datagrams), hub_status
  printed undocumented freq field, forecast human display double-converted
  Fahrenheit stations (units_temp=f is documented and honored), SK/AR
  device types now matched alongside SKY/AIR, StationSet unwrap handles
  stations/locations/bare-list shapes, missing ~/.tempest.env fallback
  implemented as documented, dry-run stations plan, handler-owns-flags
  dispatch. Added decode_message()/handle_datagram() type-dispatch layer
  covering all seven UDP message families.
- scripts/test_tempest.py: 42 offline tests (pytest + unittest green,
  proxy-trap clean) - canned UDP datagram bytes fed to the decoder with no
  sockets, mocked REST transport, help/arg-error/dry-run classes, and the
  documented pipelines (stations->current, obs day totals, forecast units).
- SKILL.md: lastfm-model rewrite (275 lines) - Setup, intent-grouped
  commands, UDP family dispatch table, pipeline recipes, jq guidance, ten
  grounded gotchas, when-to-use/when-not-to-use boundaries, reference
  routing table.
- README.md: human-format refresh with hub-on-LAN prerequisite.
- evals/evals.json: 8 schema-v1 cases incl. two negative probes
  (Shakespeare The Tempest, generic city forecast).
- Root README blurb and references/skill-triggers.md row synced to the new
  description; .claude-plugin/marketplace.json and llms.txt regenerated
  (both embed descriptions; check modes exit 0; codex artifact unaffected).

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

.claude-plugin/marketplace.json

@@ -1245,7 +1245,7 @@
         "./tempest"
       ],
       "strict": false,
-      "description": "Query hyper-local weather from a WeatherFlow Tempest station: current conditions, 7-day forecast, historical observations, and real-time UDP broadcasts. Use when the user asks about the weather, temperature, rain, wind, humidity, forecast, or wants conditions from their own station rather than a generic weather service."
+      "description": "Query hyper-local weather from a WeatherFlow Tempest station over its REST API and the hub's local UDP broadcast: current conditions, forecast, historical observations, and real-time decoded datagrams (obs_st, rapid_wind, evt_precip, evt_strike, hub_status). Use when the user asks about weather, temperature, rain, wind, humidity, or forecast data from their own Tempest/WeatherFlow station, or wants to parse the hub's UDP port 50222 broadcast. Do not use this skill for generic or city forecasts without a Tempest station (public weather services serve those), for Shakespeare's play The Tempest or other literature questions, or for weather hardware from other vendors - the REST endpoints require a personal-use token and the UDP broadcast only exists on a Tempest hub's LAN."
     },
     {
       "name": "terraform",