feat: show re-up opportunity per receipt on unlock page

[thedavidmeister]

Closes #237. Reimplements #238 on a fresh branch off current main (multi-network).

Summary

• Adds re-up visibility to the Unlock page: how much additional cyToken each receipt could mint at the current lock price without locking more underlying.
• New columns (toggleable): Addl {token.name} per 1 {token.underlyingSymbol} and Total addl {token.name}.
• Grand total card sums re-up across all visible receipts.

Math

• addlPerUnderlying = max(0, currentLockPrice − tokenId) (both 18-decimal prices)
• totalsFlr = (balance × 1e18) / tokenId (in token.decimals)
• reupTotal = (totalsFlr × addlPerUnderlying) / 1e18 (in token.decimals)

currentLockPrice reads $balancesStore.stats[token.name].lockPrice, so values recompute reactively when prices refresh.

Differences from #238

• Uses formatUnits(value, token.decimals) / formatUnits(value, 18) instead of formatEther, since the multi-network refactor on main means token.decimals may not be 18 (e.g. cyWETH on Arbitrum).
• Computes currentLockPrice once at the top of the reactive block instead of per-receipt.

Test plan

• Existing ReceiptsTable.test.ts still passes
• Full vitest suite (279 tests) passes
• Manually verify on Flare (cysFLR) that toggle hides/shows columns and grand total
• Manually verify on Arbitrum (cyWETH) that decimals render correctly

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