fix: Entitlements issues #2

[azhur]

Description

• Subscription entitlements now return effective (merged + live usage) instead of raw rows; plan version and add-on entitlements return resolved (merged, no usage)
• activation_date fixed from NaiveDate to NaiveDateTime — preserves sub-day precision for fixed-window reset periods
• PendingEntitlementsPanel hardcoded "quote" label replaced with entityLabel prop, making it reusable for subscriptions
• OpenAPI spec regenerated

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.