feat(core): full memo type support and SEP-29 memo-required checks

[Meemlahsabi]

Overview

This PR adds full Stellar memo type support to useSendPayment — MEMO_TEXT, MEMO_ID, MEMO_HASH, and MEMO_RETURN — with pre-flight validation and SEP-29 memo-required checks so exchange deposits are credited correctly instead of silently landing in an omnibus account.

Related Issue

Changes

📝 Full Memo Type Support

• [ADD] MemoInput in packages/core/src/types/index.ts
  • SendPaymentOptions.memo widened from string to MemoInput.
  • Bare strings remain MEMO_TEXT for backwards compatibility.
• [MODIFY] useSendPayment in packages/core/src/hooks/useSendPayment.ts
  • Validates each memo type before building the transaction.
  • text is measured in UTF-8 bytes (TextEncoder) and limited to 28 bytes.
  • id stays a string end-to-end and is passed directly to Memo.id() — no Number parsing, so values above Number.MAX_SAFE_INTEGER are preserved.
  • hash/return require exactly 64 hexadecimal characters.
• [ADD] INVALID_MEMO code in packages/core/src/errors/codes.ts
  • Actionable error messages name the limit and the supplied value instead of surfacing as UNKNOWN.

🛡️ SEP-29 Memo-Required Checks

• [ADD] Pre-submission destination check in useSendPayment
  • Loads the destination account only when no memo is supplied and the destination is not a muxed M... address.
  • Looks for the config.memo_required data entry; if present, refuses with MEMO_REQUIRED.
  • Rejects a muxed destination combined with an explicit memo before any round trip.

🧪 Tests & Docs

• [ADD] packages/core/src/hooks/useSendPayment.test.tsx
  • Pins the bare-string MEMO_TEXT path.
  • Covers byte-length text memos with emoji/CJK.
  • Uses an id above Number.MAX_SAFE_INTEGER and asserts the exact value on the built transaction.
  • Covers INVALID_MEMO for non-numeric id and bad hash/return.
  • Covers MEMO_REQUIRED, skip conditions, and muxed + memo rejection.
• [MODIFY] docs/hooks/use-send-payment.md
  • Prominent note about exchange deposits requiring MEMO_ID.

Verification Results

pnpm test
✅ All tests pass

pnpm lint
✅ No lint errors

pnpm typecheck
✅ Typecheck passed

pnpm build
✅ Build passed

Acceptance Criteria	Status
All four memo types build correctly and appear on the submitted transaction	✅
memo: "hello" still produces MEMO_TEXT — no breaking change	✅
A text memo over 28 bytes fails validation with a clear message before any network call, not as UNKNOWN	✅
A multi-byte (emoji/CJK) memo is measured in bytes, and a test proves it	✅
An id memo is carried as a string end-to-end; a test uses a value above Number.MAX_SAFE_INTEGER and asserts the exact value on the built transaction	✅
Non-numeric id, and hash/return that are not 64 hex chars, are rejected with INVALID_MEMO	✅
Sending to an account with config.memo_required and no memo fails with MEMO_REQUIRED before submission	✅
The memo-required lookup is skipped when a memo is present or the destination is muxed	✅
A muxed destination combined with an explicit memo is rejected	✅
docs/hooks/use-send-payment.md documents the exchange-deposit case	✅
pnpm test, pnpm lint, pnpm typecheck, and pnpm build all pass locally	✅
No file outside "Where this lives" is touched	✅
Every example and test uses testnet only — no mainnet addresses	✅
PR description includes Closes #[issue number]	✅
Your PR targets the dev branch	✅
⭐ Leave a star on the project	✅

Closes #202

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