docs: Write a CLI manual testing guide for contributors

[AlAfiz]

Description

When new backend or smart contract developers join, they struggle to figure out how to interact with the contract locally.
We need a step-by-step markdown guide showing exactly how to use the stellar contract invoke CLI commands.
This guide should cover how to initialize the pool and execute a basic swap using dummy CLI identities.
Having this ready will drastically speed up onboarding for Wave 3.

Requirements

• Create a docs/CLI_TESTING_GUIDE.md file.
• Write out the exact bash command required to deploy the contract to a local sandbox.
• Provide the exact stellar contract invoke command to call the initialize function.
• Provide a sample command to call the swap function with dummy integer arguments.

[Code-Paragon]

Hi @AlAfiz I am an experienced DevOps Engineer very good with CLI Documentation, I can have a PR ready in 2 hours

[grantfox-oss]

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Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #77)
2. Your PR will be reviewed by the BETAIL-BOYS maintainers

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[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox as part of the Official Campaign campaign!

@Code-Paragon's PR #169 was approved and merged by @AlAfiz.

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👏 Great work, @Code-Paragon! Keep contributing to BETAIL-BOYS.