feat(extract): add OpenWeatherMap daily weather extractor

Adds extract/openweathermap package with daily weather extraction for 8
coffee-growing regions (Brazil, Vietnam, Colombia, Ethiopia, Honduras,
Guatemala, Indonesia). Feeds crop stress signal for commodity sentiment score.

Extractor:
- OWM One Call API 3.0 / Day Summary — one JSON.gz per (location, date)
- extract_weather: daily, fetches yesterday + today (16 calls max)
- extract_weather_backfill: fills 2020-01-01 to yesterday, capped at 500
  calls/run with resume cursor '{location_id}:{date}' for crash safety
- Full idempotency via file existence check; state tracking via extract_core

SQLMesh:
- seeds.weather_locations (8 regions with lat/lon/variety)
- foundation.fct_weather_daily: INCREMENTAL_BY_TIME_RANGE, grain
  (location_id, observation_date), dedup via hash key, crop stress flags:
  is_frost (<2°C), is_heat_stress (>35°C), is_drought (<1mm), in_growing_season

Landing path: LANDING_DIR/weather/{location_id}/{year}/{date}.json.gz

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

extract/openweathermap/pyproject.toml

@@ -0,0 +1,20 @@
+[project]
+name = "openweathermap"
+version = "0.1.0"
+description = "OpenWeatherMap daily weather extractor for coffee-growing regions"
+requires-python = ">=3.13"
+dependencies = [
+    "extract_core",
+    "niquests>=3.14.1",
+]
+
+[project.scripts]
+extract_weather          = "openweathermap.execute:extract_weather"
+extract_weather_backfill = "openweathermap.execute:extract_weather_backfill"
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+packages = ["src/openweathermap"]