deduplicate met writes

[dlebauer]

Convert weather once per ERA5 grid and ensemble member.

This eliminates ~90% of the duplicated writes, may avoid potential issues with concurrent writes.

[Copilot]

Copilot review overview

🟢 Approval recommended

The deduplication matches the grid-based input and output paths without altering downstream behavior.

Review effort: Balanced
Findings: None

What changed in this PR

Deduplicates ERA5 meteorology conversion jobs by grid cell and ensemble member.

Changes:

• Retains one location per ERA5 grid cell before expanding ensemble IDs.

File	Description
workflow/​01_ERA5_nc_to_clim.R	Prevents duplicate clim-file writes for sites sharing a grid cell.

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[infotroph]

eliminates ~90% of the duplicated writes

met2model.SIPNET is run with overwrite = FALSE here, so duplicated writes are skipped already.

The original design here was that to support both site-specific and gridded use cases with the same script. To convert a convert a whole grid users would pass an already deduplicate list of cell locations; to convert a few sites users would pass the site_info and it would write each output by site_id without checking for duplicate file content. Now that we write by cell name instead, I guess that means the site-specific use case was already removed and we can move the deduplication a step earlier.