Export: per-layer spatial reference (WKID/WKT)

[danmaps]

Why

Automation decisions (buffer distance, projection, performance) depend heavily on knowing each layer’s spatial reference.

Proposal

Include spatial reference info per layer in snapshot/context:

• spatialReferenceWkid when available
• spatialReferenceName (optional)
• spatialReferenceWkt (optional, but helpful when WKID missing)

Acceptance Criteria

• Each exported layer includes SR metadata when obtainable.
• Export remains safe-by-default (no raw data exfil) and fast.

Notes

If per-layer SR is expensive, fall back to map SR plus an unknown marker and a warning.