v0.10.0 — The Unix legs build with Ninja

Nine workflows configured with no -G and got Unix Makefiles, which cost twice
over: cmake --build shells out to make with no -j, so those legs compiled
on one core of the runner's four, and Makefiles cannot scan C++20 module
dependencies at all.

They now take a generator input, defaulting to Ninja — gcc, clang,
clang-libc++, apple-clang, coverage, sanitizers, clang-tidy, codeql
and consumption, the last across all five of its configure sites. Nothing is
installed: ubuntu-24.04, macos-15 and macos-26 all ship Ninja 1.13.2. A caller
needing the platform default writes generator: Unix Makefiles; mingw.yml and
the two Visual Studio legs already named their own and are unchanged.

Also since v0.9.0:

• vcpkg_features lets a caller name the manifest features its tests need,
  instead of pushing them into default-features and charging every consumer
  for them (#45).
• The internal pins name a commit the history can serve. A repin made on a
  branch is stale the moment it squash-merges, which had left main and every
  PR red on 58 bad pins (#47).
• The README claims Active rather than WIP, and says what this CI is
  indifferent to — the shape of the library, the test framework — rather than
  defending it (#46, #48, #49).

Upgrading: repin and nothing else, unless your project depends on the
generator. The build directory is CMake's own, so a caller that cached one
across the change wants a clean configure.