Add Ireland OPW

[thiagovmdon]

Summary

Related to issue #95

Implemented:

• new IrelandOPWFetcher
• integration in rivretrieve/__init__.py
• fetcher documentation
• cached station metadata
• example script
• unit tests with local sample fixtures

Data source

Source:

• Office of Public Works (OPW), Ireland
• https://waterlevel.ie
• Hydro-Data API: https://waterlevel.ie/hydro-data/#/html/API

Endpoints used:

• station metadata:
  https://waterlevel.ie/hydro-data/data/internet/stations/stations.json
• time series archive:
  https://waterlevel.ie/hydro-data/data/internet/stations/0/{station_id}/{parameter}/year.json

Supported variables

The new fetcher supports RivRetrieve-native daily mean variables only:

• constants.DISCHARGE_DAILY_MEAN
• constants.STAGE_DAILY_MEAN
• constants.WATER_TEMPERATURE_DAILY_MEAN

Parameter mapping:

• Q -> discharge daily mean
• S -> stage daily mean
• TWater -> water temperature daily mean

When OPW returns min / mean / max products in the same response, the fetcher explicitly selects the daily mean series.

Implementation notes

The implementation follows the existing RivRetrieve fetcher patterns used for:

• Belgium Flanders
• Germany Berlin
• Switzerland

Key points:

• metadata is fetched live from stations.json
• cached metadata is stored in rivretrieve/cached_site_data/ireland_opw_sites.csv
• gauge IDs use OPW station_no
• padded and non-padded station IDs are both accepted
• metadata is filtered to station IDs in the 1..41000 republication-safe range from the original OPW logic
• date filtering is done client-side after reading the yearly archive payload

Files added / updated

Added:

• rivretrieve/ireland_opw.py
• docs/fetchers/ireland_opw.rst
• examples/test_ireland_opw_fetcher.py
• rivretrieve/cached_site_data/ireland_opw_sites.csv
• tests/test_ireland_opw.py
• Ireland OPW test fixtures in tests/test_data/