API docs: `group_treasury` contract interface

[codebestia]

Write contracts/docs/api-group-treasury.md documenting every public function in contracts/contracts/group_treasury/src/lib.rs — initialize, get_threshold, add_member/remove_member, is_member/get_members, deposit/withdraw/balance, and the multisig withdrawal-proposal functions (propose_withdraw, approve_withdraw, reject_withdraw, get_proposal, list_proposals, get_pending_proposals).

Acceptance criteria:

• Every public function is documented with its full signature, authorization requirements, and panics/error conditions
• The multisig withdrawal flow (propose_withdraw → approve_withdraw×N → execution) is documented as a worked example end-to-end
• Verified against the current lib.rs

[Malcolm-Wander]

@Malcolm-Wander has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello maintainer,I’d love to work on this issue please,I promise to do a good and swift job..thank you.

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

[blurbeast]

@blurbeast has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

hello my Chief, can i jump on this please ??

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[devgbmuyiwa]

@devgbmuyiwa has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

hello can i work on this issue

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[Anthony-19]

@Anthony-19 has applied to work on this issue as part of the Stellar Wave Program's 7th wave.

Hello Maintainer, I am a developer with years of experience, I would love to jump on this

ℹ️ Repo Maintainers: To accept this application, review their application or assign @Anthony-19 to this issue.

[drips-wave]

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

🧑‍💻 @devgbmuyiwa: 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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