fix(ripple): represent XRPL issued-currency amounts exactly (no float scaling)

[runninyeti]

Problem

Reported by Mesh (Mircea) while validating XRPL. The Ripple token-transfer extractor scaled issued-currency (IOU) amounts with:

const floatVal = parseFloat(deliveredOrAmount.value);
const smallestUnit = Math.round(floatVal * 1_000_000);
parsedAmount = BigInt(smallestUnit);

Two compounding errors:

1. Hardcoded * 1e6 — that's XRP's drops scaling. IOUs aren't denominated in drops; their value is an arbitrary-precision decimal (up to 15 significant digits, wide exponent) with no fixed integer unit and no universal decimals.
2. parseFloat + Math.round — lossy on large / scientific-notation values.

Observed on live ledger 105011630:

token	real value	old amount	correct
BITx	0.00026764546195073	268	0.00026764546195073
USDV	7979.002624671	7979002625 (rounded)	7979.002624671
MAG	0.00001	10	0.00001

Native XRP (integer drops) was already correct.

Fix

• Parse the IOU value losslessly into (mantissa: bigint, decimals: number) using string/BigInt math — never parseFloat. Handles plain and scientific-notation values; trims trailing fractional zeros to a minimal scale.
• Add an optional NetworkTransfer.decimals field (additive, non-breaking), populated only for IOUs. human = amount / 10 ** decimals. This mirrors how EVM token amounts already work (raw integer + decimals applied out-of-band). Native XRP / EVM / all other paths are unchanged — no decimals emitted, so existing consumers and tests are unaffected.
• Decode 40-hex XRPL currency codes to their ASCII symbol (e.g. BITx) instead of emitting the raw hex blob; non-printable codes (LP tokens, etc.) keep the hex.

Verification

• New inline tests cover the fractional (the 268 regression), large-whole, and scientific-notation cases, plus hex-currency decode.
• Existing native-XRP and failed-payment (fee-only) tests pass unchanged.
• Spot-checked against live ledger 105011630 — BITx / USDV / MAG now reconstruct to their exact on-ledger values.

Note on token identity

token is set to the (decoded) currency code, preserving prior semantics. XRPL IOUs are uniquely identified by currency + issuer, so same-symbol tokens from different issuers still collide on token alone — out of scope here, worth a follow-up if we need issuer-level disambiguation.

🤖 Generated with Claude Code