Add Agency Name default value to field mappings

- Added FERRERO.MARKETING.FIELD.AGENCY NAME to defaults with value "-"
- Temporary fix while waiting for DAM admin to add "Oliver Agency" to domain
- Agency Name is a domain field (combo box) with 1938 predefined agencies
- "Oliver Agency" not currently in the list
- Using "-" as placeholder until domain is updated

Once "Oliver Agency" is added to FERRERO.MARKETING.AGENCY_NAME domain:
- Update this line to: FERRERO.MARKETING.FIELD.AGENCY NAME: "Oliver Agency"
- No code changes needed, just edit this config file

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

Python-Version/config/field_mappings.yaml

@@ -59,3 +59,4 @@ defaults:
   FERRERO.FIELD.ASSETCOMPLIANCE: "-"
   MARKETING_TAG: "Tag"
   FERRERO.FIELD.FISCAL YEAR: "2025/2026"
+  FERRERO.MARKETING.FIELD.AGENCY NAME: "-"  # Temporary - waiting for "Oliver Agency" to be added to domain