Remove cmake-build, the hpc lane name, the cc/cxx/fc aliases and the build-action fields

[mcocdawc]

Description

Removes what #97 deprecated. Closes #98.

• actions/cmake-build: builds go through a job-script recipe and run-job-script. The manifest tutorial shows eckit's recipe and ecflow's cmake_args instead of their build actions.
• cmake-build.sh.j2, the alias of cmake-atos.sh.j2.
• execution = "hpc", now a schema error; hpc-atos is the only HPC lane.
• The -hpc fallbacks: the rebuild-dispatch retry, the old names among the build workflows, and the deletion of old -hpc files on regenerate.
• The cc/cxx/fc aliases: a recipe reads c_compiler_binary, cxx_compiler_binary and fortran_compiler_binary, which default to the leg's c-compiler, cxx-compiler and fortran-compiler. Without compiler-inputs, a job title names cxx-compiler-binary, so a leg moving from cxx to cxx-compiler-binary keeps its title.
• The samples point to docs/reference/hpc.rst rather than the removed docs/howto/hpc.rst.
• The build-action fields action, forwarded-inputs, forwarded-deps-outputs and ctest, with the step that called a repo's action, the generated ctest step and _resolved.ctest/ctest-args. A triggered kind now needs a job-script in either lane. The generated "Set up Python" step reads matrix.python-version; the decode step only exported it for a forwarded input.

HPC renders stay byte-identical, so HPC_TEMPLATE_VERSION stays at 2. Docs speak of shared Jinja templates rather than a CMake template.

Draft until these are merged, since the generator validates every sibling's manifest and recipes:

• ci: test kind through a job-script recipe; name compiler binaries in *-compiler-binary ecbuild#190 (also moves its test kind to a job-script recipe)
• ci: name compiler binaries in *-compiler-binary; drop forwarded-deps-outputs eckit#369
• ci: drop forwarded-deps-outputs eccodes#586
• ci: name compiler binaries in *-compiler-binary; drop forwarded-deps-outputs ecflow#475
• ecmwf/stack-dependencies#36

Checked: with those branches as siblings, all five validate against this branch, render every leg byte-identically to main, and regenerate cross-repo-trigger*.yml without drift. metkit#293 has to switch to the *-compiler-binary names before it merges.

🤖 Generated with Claude Code

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Documentation preview
https://sites.ecmwf.int/docs/dev-section/ci-infrastructure/pull-requests/PR-103