Document setSender() requirement for owned objects in seal_approve

[alilloig]

Summary

• Add documentation tip in UsingSeal.mdx explaining that tx.setSender() is required when seal_approve references owned objects
• Add matching tip in GettingStarted.mdx quick-start guide
• Add code comments in examples/frontend/src/utils.ts near both tx.build() calls

Closes #507

Context

When a seal_approve Move function takes an owned object as a parameter (e.g., a PurchaseReceipt), tx.build({ onlyTransactionKind: true }) needs the sender address to resolve owned object inputs. Without tx.setSender(), the sender defaults to 0x0 and the build fails with an ownership mismatch error.

Current docs and examples only show shared objects + pure args, so they never encounter this. This PR fills the gap for developers using owned objects as access proof.

Test plan

• Docs-only + comment-only change — no runtime behavior change
• Verify mkdocs serve renders the new tips correctly
• Confirm existing example frontend still builds (cd examples/frontend && pnpm build)

🤖 Generated with Claude Code

[joyqvq]

you can actually use tx.build({ client: suiClient, onlyTransactionKind: true }) and the sdk will resolve the owned object without knowing the sender.

the sdk resolves this using resolveObjectReferences so setSender is not needed