Frontend: Add wallet balance insufficiency guard on deposit form

[Junirezz]

Goal

Prevent users from submitting a deposit that exceeds their actual USDC wallet balance.

Scope

• Fetch the connected wallet USDC balance on deposit modal open
• Disable the submit button and show an inline error when the entered amount exceeds balance
• Show a Max button that fills the input with the user's full available balance

Acceptance Criteria

• Submit button is disabled when amount exceeds wallet balance
• Inline error message appears below the amount input
• Max button populates the input with the correct spendable balance

[amehsamuel200225-sketch]

@amehsamuel200225-sketch has applied to work on this issue as part of the Stellar Wave Program's 5th wave.

Hi… I’m AMEH Samuel a software engineer, let me fix this issue please!.

ℹ️ Repo Maintainers: To accept this application, review their application or assign @amehsamuel200225-sketch to this issue.

[drips-wave]

Congratulations, @amehsamuel200225-sketch! 🎉 Your application was accepted by the repo's maintainers, and the issue is due on June 2, 2026.

🧑‍💻 @amehsamuel200225-sketch: 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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