feat(tokens): replace Get with Buy In, swap Withdraw for Buy More

[bmc08gt]

Token info led with "Get" for a token you don't hold and offered Give/Convert/Withdraw for one you do. Withdrawal isn't the action someone reaches for from a token's page, and there was no way to add to a position you already hold without backing out to the buy flow.

• Unowned: the single tile reads "Buy In", same OnBuy(shortfall) dispatch as before.
• Held: Give · Buy More · Convert. Withdraw drops, Convert takes its slot, and "Buy More" takes the middle with the same dispatch as the unowned tile.
• Dollars: unchanged at Give · Convert · Withdraw. There is no buying more of the cash reserve, and cashing out is what people come to that screen for. CurrencyActionTiles branches on tokenMint == Mint.usdf.

action_get had a single call site and is replaced by action_buyIn; action_buyMore already existed.

Icons. The Buy In / Buy More tiles use ic_arrow_down, exported from Figma's IconArrowDown (node 9536:8434). The Withdraw tile has no design asset to pull: the file's only IconArrowUp is the 15.8px square-cap market-cap indicator, a different family from the 28px round-cap tile glyphs, and the tile row the design draws (node 9631:2168) has no Withdraw tile at all — it puts Withdraw in a full-width text button instead. So ic_arrow_up_large is ic_arrow_down reflected about y=14, which matches the family exactly. The _large suffix is there because ui/components already owns a 20dp ic_arrow_up for the chat send button; a second drawable by that name in a module on the same classpath would silently win the resource merge.

Worth a second opinion on two things: the mirrored asset, if a designer would rather add a real 28px IconArrowUp to the file; and the fact that withdrawal is no longer reachable from a non-Dollars token's page. AppRoute.Transfers.Withdrawal still exists and is reachable elsewhere, but I didn't audit every entry point — if this tile was the primary way in, that path is gone for tokens.

Buy flow titles

SwapEntryScreen and BuyReceiptScreen were both titled "Get", so tapping a tile opened a screen that named the action something else. Both now derive the title from state.isBuyingMore, and the payment-source row reads "Buy with". Held is the same test the tile row uses — an existing token account or a positive balance — so the tile and the screen it opens always agree; SwapViewModel picks the account up from AccountController.observeHasAccountFor, which outlives a balance that has gone to zero.

title_get and label_getWith are dropped. "You Get" on the receipt breakdown is left alone; it names a leg of the trade, not the flow.

Matches code-payments/code-ios-app#671, which makes the same change on iOS.