[Contract] Optimize Storage Key Footprint in tree-token

[Idrhas]

Description

Optimize balance storage keys in the tree-token contract to minimize on-chain ledger footprint and reduce storage fees paid by users during transfers.

Acceptance Criteria

• Use compact symbols or integers for mapping keys.
• Run profiling checks to compare before/after storage fee differences.

[almuslavish]

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

i would like to work on this issue pls

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[ayomidearegbeshola29-dev]

@ayomidearegbeshola29-dev has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

I would like to work on this pls

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[teefeh-07]

@teefeh-07 has applied to work on this issue as part of the Stellar Wave Program's 6th wave.

Hi, I'll like to work on this issue.

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[Caneryy]

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

Hello, may I work on this issue?

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[drips-wave]

Congratulations, @teefeh-07! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 30, 2026.

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