Add invoice comment system

[Kingsman-99]

Label: complexity: high
Points: 200

Description

Creators and payers have no way to leave notes on an invoice. This issue adds an off-chain comment system stored in localStorage per invoice, visible only to the wallet owner, with add/delete functionality on the invoice detail page.

Technical Context

Involves invoice/[id]/page.tsx and a new src/components/CommentSection.tsx. Store comments as { invoiceId, walletAddress, text, timestamp }[] in localStorage. Only show comments belonging to the connected wallet address.

Acceptance Criteria

• Comment input and submit button on invoice detail page
• Comments stored in localStorage keyed by invoice ID and wallet address
• Comments visible only to the wallet that wrote them
• Comments can be deleted individually
• Timestamps shown in relative format (e.g. "2 hours ago")
• Mobile responsive — works on 375px screens
• No TypeScript errors

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[NnamdiCyber]

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

I can deliver an excellent work on this

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

🧑‍💻 @NnamdiCyber: 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.

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[drips-wave]

This issue has been completed by @NnamdiCyber as part of the Stellar Wave Program's 5th Wave 🥳

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