Align grace period sources across default checks and admin marking

[Baskarayelu]

Description

Unify optional grace overrides with stored protocol grace; add cross-endpoint tests.

Requirements and context

• Must be secure, tested, and documented
• Should be efficient and easy to review
• Align with existing Soroban contract patterns in quicklendx-contracts

Suggested execution

• Fork the repo and create a branch
• git checkout -b feature/grace-period-source-alignment
• Implement changes
• Write contract: src/defaults.rs, src/lib.rs
• Write comprehensive tests: src/test_default.rs
• Add documentation: docs/contracts/default-handling.md
• Include NatSpec-style comments (Rust doc comments on public items)
• Validate security assumptions

Test and commit

• Run tests
• Cover edge cases
• Include test output and security notes

Example commit message

feat: align grace period across default APIs

Guidelines

• Minimum 95 percent test coverage
• Clear documentation
• Timeframe: 96 hours

[dee-john]

@dee-john has applied to work on this issue as part of the Stellar Wave Program's 3rd wave.

Hi, I'd like to work on this issue!

Hello there, I'd love to work on this issue because I am very conversant with solving problems like this!

ℹ️ Repo Maintainers: To accept this application, review their application or assign @dee-john to this issue.

[drips-wave]

Congratulations, @dee-john! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on March 30, 2026.

🧑‍💻 @dee-john: Please resolve the issue such that the repo's maintainers have enough time to review your contribution before the due date. You'll earn Points for completing the issue on-time, which will make you eligible for a share of the Stellar Wave Program's reward pool.

Warning

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