feat(search): route Zcash addresses and block hashes

[MatiasOS]

Description

Makes the network search box work on Zcash networks.

• Addresses: transparent (t1/t3, tm/t2), Sapling (zs1, ztestsapling1), unified (u1, utest1), Sprout (zc, zt) and TEX (tex1, textest1) addresses go to /{network}/address/:address. Before this change they were rejected as an invalid search. They're only recognized while a Zcash network is selected.
• Heights: go to the block page, as before.
• 64-character hashes: Zcash block hashes and txids have the same shape, so a hash still goes to the transaction page. When no transaction matches, that page now looks the hash up as a block and redirects to it.

Related Issue

Part of #398. Stacked on #410.

Type of Change

• Bug fix
• New feature
• Documentation update
• Refactoring
• Performance improvement
• Other (please describe):

Changes Made

• useSearch: recognizes Zcash addresses, using the existing isZcashAddress util, when the selected network is Zcash.
• ZcashTransactionPage: if getrawtransaction fails for a 64-character hex hash, it tries getblock with that hash and redirects to the block page. Otherwise it shows the original error.
• e2e/fixtures/rpcMock.ts: function handlers can now return rpcError(code, message), which answers with a JSON-RPC error instead of a result.
• The Zcash RPC mock now fails the way Zebra does for unknown transactions and block hashes. It still serves:
  • the transactions spent by the fixture's inputs
  • pending transactions for mempool txids
• A hermetic e2e spec at e2e/tests/shared/mocked/zcash-search.spec.ts. It covers:
  • searching by height and by txid
  • a block-hash redirect
  • a hash that matches nothing
  • an invalid search term

Screenshots (if applicable)

N/A (no visual changes)

Checklist

• I have run npm run format:fix and npm run lint:fix
• I have run npm run typecheck with no errors
• I have run tests with npm run test:run
• I have tested my changes locally
• I have updated documentation if needed
• My code follows the project's architecture patterns

Additional Notes

• Redirect cost: redirecting a block hash takes at most three calls: the failed transaction lookup, the block lookup, and the block page's own fetch.
• Address pages: address search now routes correctly, but the address page itself arrives in the next PR of the stack. Its e2e coverage lands there too.
• Tests:
  • npm run test:run: 151 passing.
  • Hermetic Zcash e2e specs (dashboard, blocks, transactions, mempool, search): 16 passed.