FINERACT-2177: enforce traditional merge strategy

[meonkeys]

PLEASE REVIEW BUT DO NOT MERGE YET

Per FSIP-7, please do not merge until Monday, March 23rd, 2026

Description

FINERACT-2177

Enforce new policy from FSIP-7.

In order to preserve commit signatures in git commit history (and with the added benefit of additional provenance), we had to change our merge stragegy so, when merging PRs into develop, we do not also clobber signatures.

Checklist

Please make sure these boxes are checked before submitting your pull request - thanks!

• Write the commit message as per our guidelines
• Acknowledge that we will not review PRs that are not passing the build ("green") - it is your responsibility to get a proposed PR to pass the build, not primarily the project's maintainers.
• Create/update unit or integration tests for verifying the changes made.
• Follow our coding conventions.
• Add required Swagger annotation and update API documentation at fineract-provider/src/main/resources/static/legacy-docs/apiLive.htm with details of any API changes
• This PR must not be a "code dump". Large changes can be made in a branch, with assistance. Ask for help on the developer mailing list.

[Aman-Mittal]

lgtm