Features/#1420 update offshore wind mapping

[amir9667]

Fixes #1420.

Summary

Extends wind_offshore.py to support the new reGon2037 and reGon2045 scenarios using NEP V2025 and v2023 data, in addition to the existing eGon2035 scenario.

Changes

• Added reGon2037 and reGon2045 to the scenarios processed by wind_offshore.py. All three scenarios (eGon2035, reGon2037, reGon2045) now read from a single Excel file (NEP2035_2037_2045_V2025_2023_scnC2037.xlsx) using per-scenario capacity columns (C 2035, C 2037, C 2045).
• Updated offshore wind input handling to read the new NEP dataset.
• Extended NVP-to-OSM substation mappings for new connection points.

Validation

-Tested against the Schleswig-Holstein boundary.

• Verified successful execution of the offshore wind insertion workflow.
• Verified mapping of new connection points to existing substations.
  -Checked resulting installed capacities against the provided NEP input file.
• Note: the NEP V2025 Excel currently exists in two versions and should be reconciled so that testing and the pipeline run against the same input data.

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