Add regression test for staked keys excluded from sell balance check

[Chucks1093]

Summary

A holder's staked keys must not be counted as available for selling. Attempting to sell an amount that would require dipping into staked keys should revert even if the total key balance (liquid + staked) is sufficient.

Scope

• Give a wallet 10 keys: stake 6, leaving 4 liquid
• Attempt to sell 5 keys and assert it reverts with insufficient liquid balance error
• Assert selling exactly 4 keys succeeds

Acceptance Criteria

• Sell of 5 reverts when only 4 liquid keys available
• Sell of 4 succeeds using only liquid balance
• Staked balance unchanged after both attempts

ETA: 12 hours

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Coordinate on Telegram

[GBOYEE]

Hey team — I'd like to take this on (Add regression test for staked keys excluded from sell balan). I'll write the missing test coverage and wire it in. I'll open a PR referencing this shortly once assigned.

[Unclebaffa]

Hi Maintainer,
I’m interested in contributing to this issue and believe I can deliver a clean, well-tested solution that aligns with the project’s standards.
Thank you

[grantfox-oss]

🦊 GrantFox — @Unclebaffa has been assigned to this issue as part of the Official Campaign | FWC26 campaign!

Next steps:

1. Open a Pull Request referencing this issue (e.g., Closes #546)
2. Your PR will be reviewed by the accesslayerorg maintainers

Good luck! Track your progress on GrantFox.

[grantfox-oss]

🎉 This issue has been marked as completed on GrantFox!

@Unclebaffa's PR #563 was approved and merged by @Chucks1093.

🏆 @Unclebaffa: You earned 45 FoxPoints for this contribution! Your current tier: Specialist (4,619 total points). Track your full progress on GrantFox.

👏 Great work, @Unclebaffa! Keep contributing to accesslayerorg.