v0.6.1

Fixed

• natmod's x86 arch failed to link through natmod_host, on every tag
  through v1.28.0, since 0.6.0's own ubuntu:26.04 bump — whenever the
  module needs anything from libgcc. docker/natmod_host.Dockerfile pinned
  gcc-13-multilib by version; once the base image's own build-essential
  started resolving to gcc 15, upstream's own -m32 path for x86 (every
  MicroPython tag through v1.28.0 — v1.29.0 switched to a separate
  i686-linux-gnu- cross compiler, unaffected) linked against gcc 15's
  64-bit-only libgcc.a and failed outright (LinkError: incompatible arch)
  the moment a module actually referenced a libgcc symbol (soft-float,
  64-bit arithmetic). Fixed by computing the real, version-specific package
  name at build time (gcc-$(gcc -dumpversion | cut -d. -f1)-multilib)
  instead of typing one by hand — the unversioned gcc-multilib metapackage
  was tried first and does not build, since it conflicts with
  gcc-i686-linux-gnu, the other package this image has always installed
  alongside it. The image build itself now also compiles and links an
  explicit 64-bit multiply through both of x86's toolchains before the
  layer finishes, so a future regression here fails docker build, not
  just a real link somewhere downstream. x64 and every cross-compiled
  arch were unaffected. See docs/records/0068's own third correction.
• qemu's POWERNV9 board failed to link through ppc64le_linux, since
  0.6.0's own ubuntu:26.04 bump — whenever the firmware references a
  long-double printf-family call (ports/qemu's own readline.c does).
  docker/ppc64le_linux.Dockerfile installed a Debian-packaged cross
  toolchain (gcc-powerpc64le-linux-gnu + libc6-dev-ppc64el-cross), the
  same "paired with whatever gcc the base resolves to" shape natmod_host's
  multilib pin turned out to be. The base bump left the two packages out of
  step and a real link failed with undefined reference to '__snprintfieee128' — powerpc64le's own glibc long-double ABI transition.
  Fixed by replacing the apt toolchain outright with a pinned Bootlin
  tarball (powerpc64le-power8--glibc--stable-2025.08-1, gcc 14.3.0, glibc
  2.41-70, URL + sha256 — the same model manylinux_2_41_mipsel already
  uses), rather than chasing the Ubuntu packaging mismatch: Bootlin's own
  gcc and glibc come from one matched Buildroot build, so there is no
  separately-packaged "-cross" half left to drift from the compiler's own
  version. Verified against the exact failing call shape
  (snprintf/%Lf on a long double), statically linked, both directly
  through the extracted toolchain and inside a real docker build of the
  changed image. See docs/records/0068's own fourth addendum.