fix: TypeError in invite_user_v1 due to schema mismatch

[sentry]

This PR addresses issue DALGO-BACKEND-2FB, a TypeError: Object of type DjangoGetter is not JSON serializable occurring at the /api/v1/organizations/users/invite/ endpoint.

Root Cause:
When an invitation was resent, the invite_user_v1 function in ddpui/core/orguserfunctions.py returned an InvitationSchema object (generated by from_invitation(invitation)) that was missing the invited_role_uuid field. This field is required by the API's declared response schema (NewInvitationSchema), leading to a PydanticValidationError. Subsequently, when the system attempted to serialize this validation error for the API response, the exc.errors() object contained DjangoGetter instances, which are not JSON serializable, resulting in the observed TypeError.

Changes Made:

1. Corrected Response Schema (ddpui/core/orguserfunctions.py): Modified the invite_user_v1 function to explicitly construct and return a NewInvitationSchema object with the invited_email and invited_role_uuid (from invitation.invited_new_role.uuid) when an invitation is resent. This ensures the returned data conforms to the expected schema.
2. Robust Error Serialization (ddpui/routes.py): Added a try-except TypeError block within the pydantic_validation_error_handler. If exc.errors() contains non-serializable objects, the handler will now gracefully convert the entire error detail to a string, preventing the TypeError and ensuring a valid JSON response.

Fixes DALGO-BACKEND-2FB

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 60.26%. Comparing base (11a5843) to head (93be07e).

Files with missing lines	Patch %	Lines
ddpui/core/orguserfunctions.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1418   +/-   ##
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  Coverage   60.26%   60.26%           
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  Files         146      146           
  Lines       17222    17222           
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  Hits        10378    10378           
  Misses       6844     6844           

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