test(lending): Add regression suite for missing-derive bug class

[nanaf6203-bit]

Implement a linter + test suite that asserts all pub-storage types derive Encode, Decode, TypeInfo, and StorageLayout when relevant.

[Spycall]

@Spycall has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

i would love to handle this.

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

[drips-wave]

Congratulations, @Spycall! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

🧑‍💻 @Spycall: 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.

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