chore: Standardize local_ids/external_ids/alias and clean plan apis

[gaspb]

Description

& advance Plan screens (remove billing periods, add copy-able local_ids, add version list, add subscription count, simplify draft/active version management)
& add FK to product_id, rename product_item_id to product_id (to match the db table)

Checklist

• The code follows the project's coding conventions and style guidelines.
• All tests related to the changes have passed successfully.
• Documentation has been updated to reflect the changes (if applicable).
• All new and existing unit tests have passed.
• I have self-reviewed my code and ensured its quality.
• I have added/updated necessary comments to aid understanding.