Add helper utility for formatting Stellar asset amounts

[Cjay-Cyber-2]

Description — what to implement and the why/impact.

Stellar ledger amounts are often represented in stroops or raw string decimals. Having a dedicated helper utility to format and parse Stellar asset amounts cleanly avoids precision errors and standardizes display across API responses.

Context & Requirements — background, constraints, design references, edge cases;

• Grounded in src/utils/ or src/services/.
• Must handle standard decimal string conversions safely without floating-point inaccuracies.
• Adhere to TypeScript strict type checking.

Acceptance Criteria — a checklist ("- [ ] ...") of specific, testable conditions that define "done^".

• Implement asset amount formatting and parsing helper functions.
• Add unit tests covering zero, standard decimal values, and large integer edge cases.

Implementation Guidance — likely files/modules to touch

• Likely files: src/utils/stellar.ts or a new src/utils/format.ts file.
• Suggested approach: Use standard JavaScript BigInt or string manipulation helpers suitable for Stellar asset precision.

Testing & Validation — how the contributor should prove it works

• Run npm test to confirm unit tests pass successfully.

Submission Guidelines — must open a PR that includes "Closes #"; assignment is required before starting.

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Wave complexity: Trivial

[graceanya796-maker]

@graceanya796-maker has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello
I would love to work on this issue please

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[Priest-Codes]

@Priest-Codes has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi maintainer! I'd love to work on this issue. I can start as soon as possible and will provide a fix promptly. Could you please assign it to me?

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[Glittersup]

@Glittersup has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi! I’m interested in this issue. I can trace the existing implementation, identify the appropriate integration points, and implement the change with minimal disruption to the surrounding code. I’ll also cover the relevant tests and edge cases before submitting.

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[Tee-Gee57]

@Tee-Gee57 has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hello Maintainer, I would like to work on this issue.

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[ayandipe]

@ayandipe has applied to work on this issue as part of the Stellar Wave Program's 8th wave.

Hi maintainer,
Kindly assign issue to me for precise and prompt resolution.

Regards

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