Nuke Zcash from build infra (chain already disabled at config layer)

Removed:
- cw_zcash/ directory (Dart wrapper, no longer needed)
- assets/zcash_node_list.yml
- scripts/prepare_zcash.sh
- scripts/{android,ios,linux,macos}/build_zcash.sh
- scripts/android/docker/Dockerfile.zcash
- scripts/zcash_lib/ if cloned (rebuildable from prepare_zcash.sh which is also gone)

Edited:
- scripts/lint.sh: replaced cw_zcash loop target with the actual modules we
  ship (cw_core, cw_monero, cw_wownero, cw_bitcoin, cw_bitcoin_cash,
  cw_dogecoin, cw_evm, cw_nano).
- hashwallet.bat: trimmed mobx codegen loop to enabled chains.
- pubspec_base.yaml: dropped zcash_node_list.yml + zcash_lib sapling
  asset references.
- scripts/android/docker/{build.sh,Dockerfile.final}: removed zcash image
  build + COPY stage.

tool/configure.dart still has the zcash codegen functions intact (they
just don't fire because we don't pass --zcash); leaving them as harmless
dead code rather than risking a regression in the codegen pipeline.

scripts/macos/build_zcash.sh

@@ -1,9 +0,0 @@
-#!/bin/bash
-set -x -e
-cd "$(dirname "$0")"
-
-../prepare_zcash.sh
-
-pushd ../zcash_lib
-  ./build-scripts/mac/build-mac.sh
-popd