POST /v1/goals allows creating duplicate goals for the same category

[2u841r]

Bug: No uniqueness enforcement on goal creation

Environment: Pre-live (apis-prelive.quran.foundation)

Description

POST /auth/v1/goals?mushafId=<id> does not enforce uniqueness per user + category.
Sending a second POST with the same category returns a new id and creates a second
goal rather than returning a conflict error.

Steps to reproduce

1. POST /auth/v1/goals?mushafId=5 with body:
   { "type": "QURAN_PAGES", "amount": 10, "category": "QURAN" }
2. Note the returned id
3. POST /auth/v1/goals?mushafId=5 again with the same or different amount
4. A different id is returned — both goals now exist simultaneously

Expected

Second POST should return 409 Conflict if an active goal already exists
for that user and category.

Actual

A duplicate goal is created silently. Each POST succeeds with a new id.