feat(zcash): add address page with graceful RPC degradation

[MatiasOS]

Description

Adds the Zcash address page at /zec/address/:address and /tzec/address/:address. With this PR the stack covers every acceptance criterion in #398, including the last one: address and shielded views degrade gracefully when the RPC endpoint rejects a method.

What the page shows depends on the address type:

• Transparent (t1/t3, tm/t2): balance, total received, unspent outputs and history, all from Zebra's address index.
• Unified (u1, utest1): its receivers, from z_listunifiedreceivers. If it has a transparent receiver, that receiver's balance and history are shown too.
• Sapling and Sprout: a notice that shielded balances and history aren't publicly visible. The page makes no RPC calls for these.
• TEX and unrecognized input: a notice explaining why nothing can be looked up.

Graceful degradation. Each section of the page reports whether its data was available.

• Hosted gateways such as Tatum block the whole address index with -32601. In that case the page replaces three empty rows with one notice. It explains that a self-hosted Zebra node is needed and links to RPC settings.
• Any other failure shows a message in the affected section and a retry button.

Related Issue

Closes #398. Stacked on #411.

Type of Change

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

Changes Made

• ZcashAddressPage and ZcashAddressDisplay.
• Typed i18n keys for address types, added to the shared labels.ts.
• Routes and lazy exports for zec|tzec/address/:address.
• zcash locale strings and tooltips.zcash.address in all 5 locales.
• Styles for the address notices and the receiver list.
• Changes to the Zcash RPC mock:
  • By default, the address-index methods now return Tatum's Method not found error.
  • With addressIndex: true, it serves them the way a self-hosted node would.
• A hermetic e2e spec, e2e/tests/shared/mocked/zcash-address.spec.ts. It includes the address search test that was deferred from feat(search): route Zcash addresses and block hashes #411.

Screenshots (if applicable)

Checked locally against mocked RPC data in these states:

• a blocked address index
• a transparent address with the index available
• a unified address, at desktop width and at 400px
• a Sapling address

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

• On phones, the full unified address is truncated with an ellipsis by the shared .tx-value styles. The copy button still copies the whole address.
• AI analysis prompts for Zcash come in the last PR of the stack. They aren't part of feat: add Zcash to the explorer (adapter, pages, routes) #398's acceptance criteria.
• Tests:
  • npm run test:run: 151 passing.
  • Hermetic Zcash e2e specs (dashboard, blocks, transactions, mempool, search, address): 20 passed, with no retries.