fix: cross-subnet received amount in stake move display

[bitloi]

Closes #909

Use sim_swap.alpha_amount for the cross-subnet received amount instead of recalculating it with linear math. Add missing if not proxy: guard for extrinsic fee deduction in the cross-subnet path.

[thewhaleking]

I'll look into this more later, but I also want @ibraheem-abe's insight, specifically involving the fact it seems from this we'd be doing pricing calculations twice: once within SimSwap, and once within MovementPricing

[bitloi]

I'll look into this more later, but I also want @ibraheem-abe's insight, specifically involving the fact it seems from this we'd be doing pricing calculations twice: once within SimSwap, and once within MovementPricing

Thanks for your feedback. This PR only switches the confirmation table’s received value to sim_swap, since that’s the part that was incorrect. MovementPricing is still used for the existing spot-rate / safe-staking path. If you want to consolidate those pricing paths further, I will do that as a follow-up refactor.

[ibraheem-abe]

The previous calculation was consistent as a spot-price / linear-pricing estimate, but sim_swap is the more authoritative source for received since it reflects the runtime swap path directly.

I tried a few scenarios (dynamic -> 0, dynamic -> dynamic) and the behavior looked reasonable.
In the cases I checked, the displayed delta versus the old estimate was small, roughly 0.02% to 0.06%.