feat: add Zcash to the explorer (adapter, pages, routes) #398

Summary

Add Zcash as a first-class network in the explorer UI — adapter, pages, routes and search — mirroring how Bitcoin is wired up.

Motivation

Completes the Zcash rollout. Depends on #396 (ships ZcashClient) and #397 (network entries + type: "zcash").

Proposed Solution

Bitcoin is the closest existing template, since Zcash is a Bitcoin fork with a UTXO model plus shielded pools.

1. Types — src/types/index.ts: widen NetworkType from "evm" | "bitcoin" | "solana" to include "zcash".

2. Adapter — src/services/adapters/ZcashAdapter/ZcashAdapter.ts, modelled on BitcoinAdapter. Add a createZcashAdapter(networkId: string, client: ZcashClient) branch to adaptersFactory.ts alongside createBitcoinAdapter.

3. Pages — src/components/pages/zcash/, mirroring pages/bitcoin/: network dashboard, blocks list + detail, transactions list + detail, address, mempool. Register lazy exports in LazyComponents.tsx.

4. Routes — App.tsx, following the btc / tbtc pattern and keeping them before the :networkId catch-all:

zec, zec/blocks, zec/block/:filter, zec/txs, zec/tx/:filter,
zec/address/:address, zec/mempool, zec/mempool/:filter

plus the tzec testnet equivalents.

5. Supporting modules — src/config/zcashConstants.ts, src/utils/zcashFormatters.ts / zcashUtils.ts, src/hooks/useZcashDashboard.ts, and Zcash branches in useSearch.ts, useNetworkDashboard.ts, NavbarLogo.tsx, NetworkBlockIndicator.tsx, DataService.ts, AIPromptTemplates.ts, settings/index.tsx, plus locales/*/tooltips.json for all five languages.

What Zcash needs that Bitcoin does not

These are the parts where copying BitcoinAdapter verbatim will be wrong:

• hash_or_height is a string. getBlock, getBlockHeader and zGetTreestate take a block hash or a height as a decimal string — getBlock("3444000", 1), not a number. Easy to get wrong when porting Bitcoin call sites.
• getRawTransaction verbosity is numeric (0 = hex, 1 = object), not a boolean as in Bitcoin.
• Address-index methods take an object bag: getAddressBalance({ addresses: ["t1..."] }).
• Zcash-only response fields to surface in the UI: nonce is a 32-byte hex string (not a number), solution holds the Equihash solution, blocks carry finalsaplingroot / finalorchardroot (the latter only on post-NU5 blocks, so treat it as optional) and trees (Sapling/Orchard note-commitment tree sizes).
• Shielded transaction bundles: transactions may carry vShieldedSpend, vShieldedOutput, an orchard bundle, valueBalance, and vjoinsplit for Sprout-era transactions. A transaction can legitimately have empty vin/vout while moving value entirely within a shielded pool — the transaction view must not render those as "empty".
• Address types: transparent (t1…/t3…), Sapling (zs…), and unified (u1…). Search and address routing need to distinguish them; zListUnifiedReceivers decomposes a unified address into its receivers.
• Value pools on the dashboard: getBlockchainInfo returns per-pool balances (transparent, sprout, sapling, orchard, lockbox, ironwood) plus chainSupply — good material for the network dashboard, and genuinely Zcash-specific.

Constraints worth knowing before starting

• No WebSocket. Zebra's RPC server is built .http_only(), so there are no subscriptions. Live block updates must poll, as Bitcoin already does.
• Hosted RPC cannot serve the shielded features. The only free endpoints (Tatum) whitelist their method set: every z_* and getaddress* call returns -32601, with or without an API key — I verified this against a real key, so it is a fixed whitelist rather than a paid tier. That means address balance/history pages and any shielded-pool view require a self-hosted zebrad. See feat: add Zcash to explorer-metadata #397.
• Suggested sequencing: ship blocks / transactions / mempool / block dashboard against the hosted endpoints first, and gate the address and shielded views behind the self-hosted node.

Acceptance Criteria

• NetworkType includes "zcash"
• ZcashAdapter implemented and registered in adaptersFactory.ts
• pages/zcash/ renders network, blocks, block, txs, tx and mempool views
• zec / tzec routes registered before the :networkId catch-all
• Search resolves Zcash block hashes, heights, txids and transparent addresses
• Shielded transactions render correctly, including ones with empty vin/vout
• Tooltip locales added for all five languages
• Address and shielded views degrade gracefully when the RPC rejects the method