depends: add zeromq (wownero needs zmq.h) + cache depends save-always

wowlet.exe reached 27% then hit 'zmq.h: No such file' — feather strips zeromq from depends (its wallet does not use zmq) but wownero cryptonote_core/net does. Port the wownero zeromq.mk + patch, register it in packages. Also switch the depends caches to restore + save(if:always) so the completed toolchain banks even when the wowlet build fails (auto post-save is skipped on job failure).

.github/workflows/build.yml

@@ -160,19 +160,35 @@ jobs:
           submodules: recursive
       # depends is the slow part (static Qt6/boost/openssl/tor from source). Cache the source tarballs
       # and the compiled-package cache so only the first run pays the ~1h cost; warm runs are minutes.
-      - name: cache depends sources
-        uses: actions/cache@v4
+      - name: restore depends sources cache
+        id: cache-sources
+        uses: actions/cache/restore@v4
         with:
           path: contrib/depends/sources
           key: depends-sources-${{ hashFiles('contrib/depends/packages/*') }}
-      - name: cache depends built (mingw)
-        uses: actions/cache@v4
+      - name: restore depends built cache (mingw)
+        id: cache-built
+        uses: actions/cache/restore@v4
         with:
           path: contrib/depends/built
           key: depends-built-mingw32-${{ hashFiles('contrib/depends/packages/*', 'contrib/depends/hosts/*', 'contrib/depends/toolchain.cmake.in') }}
       - name: build depends (static Qt6 + tor + boost + openssl for mingw)
         # -j2 not -j(nproc): the parallel static Qt6 compile OOMs the 16G runner at -j4. Slower but safe.
         run: make -C contrib/depends HOST="$HOST" -j2
+      # Save depends with if:always() so the expensive toolchain banks even when the LATER wowlet.exe
+      # build fails — actions/cache's auto post-save is skipped on job failure, which kept re-paying ~2.5h.
+      - name: save depends sources cache
+        if: always() && steps.cache-sources.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: contrib/depends/sources
+          key: depends-sources-${{ hashFiles('contrib/depends/packages/*') }}
+      - name: save depends built cache (mingw)
+        if: always() && steps.cache-built.outputs.cache-hit != 'true'
+        uses: actions/cache/save@v4
+        with:
+          path: contrib/depends/built
+          key: depends-built-mingw32-${{ hashFiles('contrib/depends/packages/*', 'contrib/depends/hosts/*', 'contrib/depends/toolchain.cmake.in') }}
       - name: fetch wownerod.exe to embed
         run: |
           mkdir -p /tmp/wownerod-embed

contrib/depends/packages/packages.mk

@@ -1,4 +1,4 @@
-packages := boost openssl unbound qrencode libsodium polyseed hidapi abseil protobuf libusb zlib libgpg-error libgcrypt expat libzip zxing-cpp
+packages := boost openssl unbound qrencode libsodium polyseed hidapi abseil protobuf libusb zlib libgpg-error libgcrypt expat libzip zxing-cpp zeromq
 native_packages := native_qt native_abseil native_protobuf
 
 linux_packages := libfuse libsquashfuse zstd appimage_runtime wayland libffi

contrib/depends/packages/zeromq.mk

@@ -0,0 +1,35 @@
+package=zeromq
+$(package)_version=4.3.4
+$(package)_download_path=https://github.com/zeromq/libzmq/releases/download/v$($(package)_version)/
+$(package)_file_name=$(package)-$($(package)_version).tar.gz
+$(package)_sha256_hash=c593001a89f5a85dd2ddf564805deb860e02471171b3f204944857336295c3e5
+$(package)_patches=06aba27b04c5822cb88a69677382a0f053367143.patch
+
+define $(package)_set_vars
+  $(package)_config_opts=--without-documentation --disable-shared --without-libsodium --disable-curve
+  $(package)_config_opts_linux=--with-pic
+  $(package)_config_opts_freebsd=--with-pic
+  $(package)_cxxflags=-std=c++11
+endef
+
+define $(package)_preprocess_cmds
+  patch -p1 < $($(package)_patch_dir)/06aba27b04c5822cb88a69677382a0f053367143.patch
+endef
+
+define $(package)_config_cmds
+  $($(package)_autoconf) AR_FLAGS=$($(package)_arflags)
+endef
+
+define $(package)_build_cmds
+  $(MAKE) src/libzmq.la
+endef
+
+define $(package)_stage_cmds
+  $(MAKE) DESTDIR=$($(package)_staging_dir) install-libLTLIBRARIES install-includeHEADERS install-pkgconfigDATA
+endef
+
+define $(package)_postprocess_cmds
+  rm -rf bin share &&\
+  rm lib/*.la
+endef
+

contrib/depends/patches/zeromq/06aba27b04c5822cb88a69677382a0f053367143.patch

@@ -0,0 +1,22 @@
+From 06aba27b04c5822cb88a69677382a0f053367143 Mon Sep 17 00:00:00 2001
+From: sabotagebeats <27985126+sabotagebeats@users.noreply.github.com>
+Date: Thu, 22 Jul 2021 21:53:19 -0700
+Subject: [PATCH] fix: building libzmq fails with error src/clock.cpp:131:16:
+ error: unused variable 'nsecs_per_usec'
+
+---
+ src/clock.cpp | 1 +
+ 1 file changed, 1 insertion(+)
+
+diff --git a/src/clock.cpp b/src/clock.cpp
+index 93da90a8e..63c0100a5 100644
+--- a/src/clock.cpp
++++ b/src/clock.cpp
+@@ -195,6 +195,7 @@ uint64_t zmq::clock_t::now_us ()
+ 
+ #else
+ 
++    LIBZMQ_UNUSED (nsecs_per_usec);
+     //  Use POSIX gettimeofday function to get precise time.
+     struct timeval tv;
+     int rc = gettimeofday (&tv, NULL);