Add a per-slot account selector to the swap card's sell/buy inputs, sourced
from the wallet's token holdings, so a user holding a token in several accounts
chooses which funds each side. A single holding auto-selects.
- SwapPage fetches backend.tokenHoldings(), refetching when the wallet opens
- TokenInput embeds ProgramAccountSelector (half width, right-aligned) in a
full-width row below the amount/token row; exposes it as selectedHoldingId
- SwapCard drives swapExactInput/Output with the selected holdings and blocks
submit ("Select token accounts") until both are chosen
- ProgramAccountSelector gains showWhenSingle + textAlignment opt-ins
A shared QML select box for choosing a program account (a token holding) that
matches given criteria (accountType + a state field such as the token
definitionId), listing matches with balances and emitting selectionChanged.
Registered in the wallet module's public QML.
Cherry-picked from feat/shared-wallet-token-holding-selector, reduced to the
reusable component only; the AMM swap/liquidity wiring and FFI account source
are reimplemented on the current (post swap + createPool) code.
r4bbit