The token selector let you pick the same token on both sides of a swap.
That drove resolvePool into amm_client_pool_pda with def_a == def_b, which
hits `panic!("Definitions match")` in amm_core (a pool needs two distinct
tokens). Because that panic crosses the `#[no_mangle]` FFI boundary — which
can't unwind — it aborts, taking the whole UI process down.
Guard it at the source: the picker now disables (dims, no hover/click, tags
"Selected") whichever token is already chosen on the opposite side, so the
two sides can never match.
- TokenListItem: add a `disabled` state (opacity, inert MouseArea, tag)
- TokenSelectorModal: add `disabledDefinitionId`; gate both the popular-token
pills and the list rows on it
- SwapPage: on open, set it to the opposite side's selected token
r4bbit