FINERACT-2684: WC - Ensure consistent disbursement date handling

[adamsaghy]

Description

Describe the changes made and why they were made. (Ignore if these details are present on the associated Apache Fineract JIRA ticket.)

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[utafrali]

Good refactoring that correctly fixes the findFirst()/getFirst() ordering bug by centralising chronologically-ordered disbursement lookups on the domain object. The main gap is that WorkingCapitalLoanMapper still gates setActualDisbursementDate on disbursedBy != null, leaving the full-loan timeline inconsistent with the summary mapper — directly at odds with the PR's stated goal.

[budaidev]

LGTM