feat(adapter): add Zcash data layer

[MatiasOS]

Description

Adds the Zcash data layer:

• Domain types.
• A ZcashAdapter over the Zebra RPC.
• Wiring so DataService builds that adapter for type: "zcash" networks.

There is no UI yet; the pages land in the next PRs of the stack.

The adapter is designed around hosted gateway limits. Tatum allows about 5 requests per minute per IP and blocks the address index:

• Blocks: heights go straight to getblock as decimal strings, so one block costs one call, with no getblockhash or header round trip.
• Failures: a failed call throws a typed ZcashRpcError (unsupported, rateLimited or failed) instead of returning empty data.
  • A rate-limited call is retried after 15s, then after 30s.
• Addresses: each address section reports its availability (ok, unsupported or error), so pages can degrade when the address index is blocked.
• Input values: Zebra omits transparent input values. They are resolved on demand, capped at 10 previous transactions.

Related Issue

Part of #398. Stacked on #405.

Type of Change

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

Changes Made

• src/types/index.ts: NetworkType gains "zcash", plus new Zcash types for blocks, transactions, shielded bundles, the mempool and addresses. Amounts are zatoshi integers.
• src/services/adapters/ZcashAdapter/:
  • The adapter and its transforms.
  • Raw Zebra shapes, including the NU6.3 Ironwood bundle and tree that the connector doesn't model yet.
  • Fixtures trimmed from mainnet block 3,483,400.
• src/utils/zcashUtils.ts:
  • Address type detection for the t1/t3/tm/t2, zs/ztestsapling, u/utest, zc/zt and tex/textest prefixes.
  • Transaction classification, fee computation from value balances, and RPC error classification.
• src/utils/zcashFormatters.ts and src/config/zcashConstants.ts.
• Wiring:
  • AdapterFactory.createZcashAdapter.
  • DataService builds a ZcashClient through ClientFactory (registry routing), and exposes isZcash() and getZcashAdapter().
  • A new isZcashNetwork() helper.
• MetadataService: Zcash genesis hashes now map to rpcs/zec/{mainnet,testnet}.json. Before, they were dropped because they didn't match the BTC mapping.
• rpcStorage: built-in Tatum zebrad defaults for both networks.
• .claude/rules/architecture.md: documents ZcashClient and ZcashAdapter.

Screenshots (if applicable)

N/A (no UI 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

• Fees on real mainnet transactions:
  • 36a167f6…ce2e3 is Ironwood only, with empty vin and vout. Fee: 10,000 zat.
  • c973d2f1…4aa7db is Sapling plus Ironwood. Fee: 20,000 zat.
• Tests: 43 new unit tests (27 in zcashUtils.test.ts, 16 in ZcashAdapter.test.ts). The full suite passes with 148 tests.
• Visibility: nothing is user-visible until the dashboard PR adds the zec and tzec network entries.
• Upstream gaps in network-connectors:
  • The Ironwood transaction bundle and trees.ironwood aren't modelled.
  • RPC error drops the JSON-RPC error code.