feat(extract): replace OpenWeatherMap with Open-Meteo weather extractor

Replaced the OWM extractor (8 locations, API key required, 14,600-call
backfill over 30+ days) with Open-Meteo (12 locations, no API key,
ERA5 reanalysis, full backfill in 12 API calls ~30 seconds).

- Rename extract/openweathermap → extract/openmeteo (git mv)
- Rewrite api.py: fetch_archive (ERA5, date-range) + fetch_recent (forecast,
  past_days=10 to cover ERA5 lag); 9 daily variables incl. et0 and VPD
- Rewrite execute.py: _split_and_write() unzips parallel arrays into per-day
  flat JSON; no cursor / rate limiting / call cap needed
- Update pipelines.py: --package openmeteo, timeout 120s (was 1200s)
- Update fct_weather_daily.sql: flat Open-Meteo field names (temperature_2m_*
  etc.), remove pressure_afternoon_hpa, add et0_mm + vpd_max_kpa + is_high_vpd
- Remove OPENWEATHERMAP_API_KEY from CLAUDE.md env vars table

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

pyproject.toml

@@ -46,7 +46,7 @@ sqlmesh_materia = {workspace = true }
 cftc_cot = {workspace = true }
 coffee_prices = {workspace = true }
 ice_stocks = {workspace = true }
-openweathermap = {workspace = true }
+openmeteo = {workspace = true }
 [tool.uv.workspace]
 members = [
     "extract/*",