feat: dollar tokens Phase 3.2 UI - virtual Dolares in Swap + Gold Buy

[TuCopFi]

Summary

Phase 3.2 UI integration. Bolts the Phase 3 foundation onto SwapScreen and GoldBuyEnterAmount/GoldBuyConfirmation. Users now see a single 'Dolares' option in the swap and gold-buy pickers that internally walks the spend order (USAT > USDm > USDC > USDT) via multi-step swaps.

Send Dolares is OUT OF SCOPE here (Phase 3.3 separate plan because Send uses transferSubmitSaga not swapSubmitSaga, and the recipient-side UX needs separate design).

What this PR contains

Architectural fix

• src/swap/useSwapQuote.ts - new fetchSwapQuoteForExecution (light fetchSwapQuote + prepareSwapTransactions) used by the orchestrator saga per step. Light fetchSwapQuote stays for UI previews.
• src/dollarsSpend/saga.ts - the saga now selects walletAddress + fromToken + feeCurrencies and calls fetchSwapQuoteForExecution so swapSubmitSaga gets real preparedTransactions per step. Foundation gap closed.

New components

• src/dollarsSpend/dolaresVirtualToken.ts - builds the synthetic 'Dolares' TokenBalance prepended to picker lists. Returns null when balances total 0.
• src/dollarsSpend/MultiSwapProgressSheet.tsx - 'Paso X de Y: convirtiendo {{symbol}}' in-flight progress.
• src/dollarsSpend/PartialSuccessSheet.tsx - 'Completaste X de Y pasos. Reintentar?' after partial failure with retry/cancel actions.
• src/dollarsSpend/DolaresMultiStepSummary.tsx - aggregate + expandable per-step breakdown shared by SwapScreen + GoldBuyConfirmation.

Screen integrations

• src/swap/SwapScreen.tsx - filters dollar tokens from the from picker, prepends Dolares row, branches confirmation render + dispatch. Existing single-swap flow unchanged.
• src/gold/GoldBuyEnterAmount.tsx - same picker filter + prepend.
• src/gold/GoldBuyConfirmation.tsx - virtual Dolares branch: multi-step plan + quote + summary + shortfall banner + executeMultiSwap dispatch. Single-token gold buy unchanged.

i18n

• locales/{base,es-419}/translation.json - new dollarsSpend.* keys (tokenLabel, confirmAggregate, expandedDetailHeader, stepCount, stepProgress, partialSuccess, shortfall).

Knip / cleanup

• knip.ts - removed the src/dollarsSpend/index.ts ignore line; UI now consumes the barrel.
• src/dollarsSpend/index.ts - trimmed to only externally consumed symbols (the rest are imported directly from their source modules where needed).

Verification

• yarn build:ts - pass
• yarn lint - pass
• yarn test - 378 suites, 4044 tests, 96 snapshots pass (existing single-swap flow tests unchanged, plus 3 new virtual-Dolares cases in SwapScreen + 3 in DolaresMultiStepSummary + 3 in dolaresVirtualToken + 4 in MultiSwapProgressSheet + 3 in PartialSuccessSheet)
• yarn knip --no-gitignore - clean for the dollarsSpend module

Known follow-ups (Phase 3.3 + later polish)

• Phase 3.3 - Send Dolares: separate plan. Multi-transfer instead of multi-swap; recipient sees N ERC-20 transfers from same sender.
• Dynamic Squid minAmount per token (V1 uses minAmountUsd=0; planner skips zero-balance, but sub-$1 dust may produce a quote that fails - acceptable per spec).
• Settings UI to revoke ERC-20 allowances (per spec follow-up).
• Permit2 / multicall integration (long-term, requires Squid native support).

Test plan

• All existing tests pass (no regression in single-token swap or gold buy)
• CI passes
• Mainnet manual QA on Android (Pixel 8 emulator + real device) with wallet holding USDT only -> single-step path
• Mainnet manual QA with wallet holding USAT + USDm + USDC -> three-step path with priority order
• Manual QA: force a failure mid-chain -> partial-success sheet appears with correct remaining USD + retry path
• Manual QA: enter amount > total Dolares balance -> shortfall banner blocks confirm