Redesign the asset rows on the create offer page - #1007

Follows #1006, which redesigned the rest of the create offer page. This PR does the asset rows inside the "You offer" and "You request" cards.

• One bordered row per asset. The amount comes first, then the asset, with the remove button inside the row. Tokens read as "100 · SBD" rather than "SBD · 100".

• Spendable balance under each offered token. For example, "500 SBD spendable". If the amount is more than that, the row turns red and says so. For XCH, the limit counts the network fee, the same as the Max button.

• "Max" text button. It replaces the up-arrow icon and fills in the same amount as before.

• Requested NFT lookup. After you paste an NFT ID, the row shows one of:

  • "This isn't a valid NFT ID." for anything that isn't an nft1… ID
  • "Looking up NFT…"
  • its name (or "NFT found" until the name is known) and the Mutable badge if its metadata can change
  • "Couldn't find this NFT…" if it doesn't exist or no peer is connected

  The lookup uses the existing getNftMetadataUpdater network lookup, which is the same one the confirmation dialog uses. No new endpoint is added.

• Removed the "Tokens", "NFTs" and "Options" sub-headings. These weren't translated. Each row's selector already shows what kind of asset it is.

• Removed the per-row z-index workaround. The dropdowns render in a portal, so it wasn't needed.

• "Part of an open offer" warning. For NFTs and options, this is now a line of text under the row instead of an icon you had to hover over.

A pasted ID is stored without surrounding spaces or newlines. Emptying the field, or typing something that isn't an NFT ID, updates the preview immediately.

What gets offered is unchanged. The over-balance message is a warning only and doesn't block creating the offer, the same as before. I created an offer end to end in the sandbox: two tokens and two NFTs offered, a token and someone else's NFT requested.

Review

Two review rounds, each run with separate correctness, tests and simplification reviewers. Round 1 found that the thumbnail never appears for an NFT the wallet doesn't hold. getNftThumbnail reads only NFTs whose coin the wallet holds, and a requested NFT usually belongs to someone else. So the preview no longer shows a thumbnail; see the decision below. Other fixes:

• Trim pasted IDs.
• Clear a stale preview straight away.
• Tests for the lookup's debounce and late results, the preview's states, amounts at the spendable balance, the fee only counting against XCH, and requested tokens showing no balance or Max.

Round 2 found nothing at major or above.

Decisions to confirm

• No thumbnail in the requested NFT preview. Showing one, and refreshing the name once the NFT's metadata downloads, needs a backend change: for example, returning the saved asset's icon and name from the lookup for an NFT the wallet doesn't hold.
• No royalty in the NFT preview. No existing endpoint returns a requested NFT's royalty, so showing it would need a new RPC endpoint.
• Over-balance is a warning, not a block. The Create Offer button stays enabled, as it was before.
• New wording for the row messages above.

New strings are wrapped with Lingui; the next release needs pnpm extract.