fix(explorer): tolerate per-token metadata failures on block page

[web3jacker]

🩹 One bad token shouldn't blank out a whole block's events

Hey! Small but annoying one here.

On the block page we collect every TIP-20 address that shows up in the
receipts, then fetch metadata for all of them at once:

const metadataResults = await Promise.all(
  tip20Array.map((token) => client.token.getMetadata({ token })),
)

Problem: Promise.all is all-or-nothing. If one token doesn't conform to the
TIP-20 metadata interface, or the RPC just hiccups on a single call, the whole
thing rejects — and blockKnownEventsQueryOptions fails with it. So a single
weird token means none of the transactions on that block get their
known-events rendered. 😬

The funny thing is the receipts fetch right above it already does the right
thing with .catch(() => null), and the loop that consumes the metadata
already null-checks each entry. So this was just an inconsistency.

The fix is to make the metadata fetch match:

tip20Array.map((token) => client.token.getMetadata({ token }).catch(() => null))

Now a flaky/non-conforming token just doesn't get decorated metadata, and
everything else on the block renders fine. 👍