Add OpenWrt SDK packaging under src/Build for console-only x86/64 builds. The build helper prepares the SDK, renders a local package recipe, builds VeraCrypt with the OpenWrt musl toolchain, uses wxWidgets 3.2.10 as static wxBase, enables FUSE3, and skips release self-tests during cross compilation.
Add a package template that installs the console binary, mount.veracrypt, and license files only. The package declares bash for mount.veracrypt and keeps runtime dependencies focused on the direct userland requirements.
Add a documented QEMU runtime test path that boots the matching OpenWrt image, installs the locally built package set with opkg, runs the VeraCrypt version and algorithm self-tests, and exercises a small filesystem=none container mount/unmount flow.
Allow wxbuild callers to pass WX_CONFIGURE_EXTRA_FLAGS so OpenWrt cross configure flags can be passed into the wxWidgets build without carrying an OpenWrt-specific source patch.