Do not allow the creation custom resource fields if that field already exists as a global.

Feature Request: Prevent Duplicate Proposal Resource Fields

Summary:
Add validation to prevent users from creating proposal-level resource fields with the same name as existing global resource fields. This will ensure consistency between proposal and global configurations and eliminate submission errors when sending data to Contractor Edition (CE).

Problem Statement:
Currently, users can create proposal-level resource fields that have the same name as global resource fields. This creates ambiguity in the data model and leads to conflicts when proposals are submitted to Contractor Edition (CE). These conflicts can cause submission errors, unexpected behavior, or require manual cleanup, increasing support burden and delaying proposal processing.

Proposed Solution:
Validate new and edited proposal-level resource field names against the global Resource field list.
If a user attempts to create or rename a proposal-level resource field to a name that already exists globally, block the action and display a clear error message indicating that the name is reserved by a global field.
Provide a way for users to view or reference the global Resource field list (e.g., via a lookup or tooltip) when configuring proposal-level fields so they can choose non-conflicting names.
Apply this validation consistently across all relevant entry points (UI, imports, APIs) where proposal-level resource fields can be created or modified.

Benefits:
Prevents data conflicts and submission errors when sending proposals to Contractor Edition (CE).
Improves data integrity by enforcing a single source of truth for resource field definitions.
Reduces support and troubleshooting time associated with misconfigured proposal-level fields.
Provides clearer guidance to users during configuration, reducing confusion and configuration mistakes.