Implement hydroviz webapp-specific endpoint based on new water temperature endpoints

[cstephen]

Closes #725.

This PR adds/aggregates the new water temperature endpoints implemented in #727 to the (hidden) hydroviz-webapp-specific endpoint (e.g., http://localhost:5000/arctic_hydrology/hydroviz/81033944). The following properties have been added to the API response:

• max_temp_dates
• monthly_temperature
• wt_hydrograph
• wt_stats

These new properties contain all of the data needed to add a few new chart/table components for Alaska stream segments in the hydroviz webapp:

• temperature hydrograph
• monthly temperature chart
• max temperature & date chart
• a few new temperature-based stats tables.

To test, point the wt_charts_and_table branch of the hydroviz webapp (ua-snap/hydroviz#228) against this wt_hydroviz_endpoint branch of the Data API and verify that the new charts/tables listed above show up for Alaska (and Canadian) stream segments.

[Copilot]

Pull request overview

This PR extends the Arctic Hydrology arctic_hydrology/hydroviz/<stream_id> “hydroviz webapp” aggregation endpoint to include modeled water temperature data alongside the existing flow products, so the hydroviz webapp can render new temperature charts/tables from a single request.

Changes:

• Adds water temperature statistics (wt_stats) and temperature climatology-derived hydrograph (wt_hydrograph) to the hydroviz response.
• Adds derived chart payloads for monthly_temperature and max_temp_dates based on the new wt endpoints’ data structures.
• Backfills PGW model availability for water temperature similarly to the existing streamflow pattern by fetching original_gcm and merging.

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[BobTorgerson]

This returns a lot of additional data for the visualizations, I tested it on a number of different HUC IDs to validate that the data is returning consistently. For the amount of data that is returned, it returns data very quickly. Approved!