feat(widget): add redesigned amount input cards for jumper modes

[effie-ms]

Which Linear task is linked to this PR?

EMB-452

Why was it implemented this way?

This adds a redesigned amount input as Send/Receive cards, rendered exclusively in jumper-simple and jumper-advanced widget modes. All other modes (default, split, refuel, custom) continue using the existing SelectChainAndToken + AmountInput unchanged, so the redesign is fully scoped to the new modes and carries no regression risk for existing integrators.

• Send card (SendAmountCard): large editable input with adaptive font sizing, token pill selector, percentage chips (25/50/75/Max), fiat/token toggle, and wallet balance display.
• Receive card (ReceiveAmountCard): read-only amount from the best route with fiat/token toggle, token pill selector, and skeleton loading state.
• Swap button (SwapButton): vertical swap arrow between the cards (hidden in refuel mode), replicating ReverseTokensButton logic rather than duplicating it.
• The cards are composed via AmountInputCardPair and rendered conditionally from MainPage based on mode, keeping the existing layout path untouched for other modes.

New components

• AmountInputCard/ — SendAmountCard, ReceiveAmountCard, AmountInputCardPair, PercentageChips, BalanceDisplay, FiatValueToggle, shared styles
• SwapButton/ — swap arrow with overlapping card design
• TokenPillButton/ — compact pill-shaped token selector with selected/unselected variants

Builds on the Jumper modes / HeaderTabsStore work in #775 (EMB-451); this branch is based on feat/header-tabs-store.

Visual showcase (Screenshots or Videos)

TODO: add screenshots/GIFs of Send & Receive cards in jumper-simple and jumper-advanced (light + dark mode).

Test plan

• Visual check in playground with jumper-simple mode — switch all tabs (Swap & Bridge, Private, Gas)
• Visual check in playground with jumper-advanced mode — switch all tabs (Swap, Bridge, Limit)
• Token selection via pill button navigates to picker and displays selected token
• Swap button reverses from/to tokens; hidden on Gas tab
• Percentage chips set correct amounts with gas deduction on native tokens
• Fiat/token toggle works on both Send and Receive cards
• Large numbers auto-scale font size without changing card height
• Non-jumper modes (default, split, refuel, custom) render unchanged
• Dark mode renders correctly

Checklist before requesting a review

• I have performed a self-review and testing of my code.
• This pull request is focused and addresses a single problem.
• If this PR modifies the Widget API or adds new features that require documentation, I have updated the documentation in the public-docs repository.

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