Stellar fee estimation utility (Soroban + classic ops)

[truthixify]

Tier: M (2-4 days) Type: feature

Context

Stealth payment senders need to know roughly what a transaction will cost before submitting. Stellar fees depend on op count, Soroban resource budgets, and network congestion. Build a fee-estimation helper.

Scope

• estimateStellarFee({ operations, sorobanResources?, network }) returning { low, expected, high } range
• For classic ops: multiply base fee × op count, factor in network base fee
• For Soroban: simulate via simulateTransaction to get resource fee
• Considers fee-bump scenarios
• Documented uncertainty

Acceptance criteria

• Helper + tests
• Integration test against testnet
• Documentation with worked examples
• Demo follow-up to surface estimates in Send and Withdraw UI

Files to start with

• New: sdk/src/chains/stellar/fee-estimation.ts