feat(v2): card-style add-money method rows

[bmc08gt]

Summary

Redesigns the "Add Money With" purchase-method sheet for v2 as card rows — title + subtitle + trailing icon — instead of the v1 filled buttons (per Figma 8966-2140).

• BottomBarAction gains an optional content: @Composable RowScope.() -> Unit slot. When set, BottomBarView renders it as a full-width card row (own surface, ripple, click) rather than a centered CodeButton. Existing text/inline-icon actions are untouched.
• Buttons.kt builds the cards — Debit Card / Cash Reserves / Phantom / Other Wallet — when FeatureFlag.NewUi is on, gated via a FeatureFlagController injected into InternalPurchaseMethodController (which also titles the sheet "Add Money With"). The v1 buttons are unchanged. Reserves is preserved (it can appear in the Buy/swap flow where showReserves defaults true).
• Icons: Debit Card → Google Pay mark (its "Pay" wordmark recoloured white); Phantom → ghost; Other Wallet → the exact Figma QR export (ic_qr_code.xml, node 8965:5247). All 32dp; monochrome glyphs tinted white.

Also includes a nav-layout fix (separate commit): the tab bar no longer hides for BottomBar modals — that hiding collapsed the scaffold's bottom slot and re-laid-out the wallet, visibly re-fanning the collapsing card stack when Add Money opened. The modal scrim covers the bar via z-order; the bar still hides for a presented bill.

Test Plan

• :libs:messaging, :ui:components, :shared:funding, and the full app compile; :shared:funding unit tests pass; installed on emulator.
• On device: Add Money shows the card rows (correct icons, white GPay "Pay", tinted glyphs); tapping each routes correctly; the wallet card stack stays collapsed when the modal opens; v1 (NewUi off) still shows the filled buttons.

Notes

• Card surface is White10 + shapes.medium; the content-slot approach keeps the card layout in the funding module and the shared renderer change minimal.