ci: rename Checkout third-party submodules step -> Checkout mrbind submodules

[Fedr]

Summary

Make every workflow that runs the Checkout … submodules two-step pattern look the same:

1. parent Checkout does submodules: true (shallow-cloning all 29 top-level submodules at the parent's fetch-depth: 1),
2. a single follow-up step recursively fetches only thirdparty/mrbind's nested sub-submodule (deps/cppdecl) — the only path under thirdparty/ that has its own .gitmodules.

Why

Of the 29 top-level submodules in MeshLib, only thirdparty/mrbind has nested sub-submodules. So the second step is genuinely only about mrbind on every workflow — but the previous step name ("Checkout third-party submodules") suggested a broader scope, and most workflows had a long selective list of submodules in the git submodule update line that hid the actual intent and caused drift between workflows.

$ for sm in thirdparty/mrbind thirdparty/imgui thirdparty/eigen \
            thirdparty/parallel-hashmap thirdparty/mrbind-pybind11 \
            thirdparty/fastmcpp thirdparty/nlohmann-json thirdparty/cpp-httplib ; do
    echo "=== $sm ==="
    [ -f $sm/.gitmodules ] && cat $sm/.gitmodules || echo "(no .gitmodules)"
done
=== thirdparty/mrbind ===
[submodule "deps/cppdecl"]
        path = deps/cppdecl
        url = https://github.com/MeshInspector/cppdecl
=== thirdparty/imgui ===          (no .gitmodules)
=== thirdparty/eigen ===          (no .gitmodules)
=== thirdparty/parallel-hashmap ===   (no .gitmodules)
=== thirdparty/mrbind-pybind11 ===    (no .gitmodules)
=== thirdparty/fastmcpp ===       (no .gitmodules)
=== thirdparty/nlohmann-json ===  (no .gitmodules)
=== thirdparty/cpp-httplib ===    (no .gitmodules)

Files changed (8 workflows)

Workflow	Change
build-test-macos.yml	step renamed + comment expanded (parent already had submodules: true; submodule list already only thirdparty/mrbind)
build-test-windows.yml	same as macos
build-test-emscripten.yml	+ submodules: true on parent; submodule list trimmed to just thirdparty/mrbind; step renamed
build-test-linux-vcpkg.yml	same
build-test-ubuntu-arm64.yml	same
build-test-ubuntu-x64.yml	same
pip-build.yml	same; also drops the per-submodule safe.directory lines that only existed for the previous selective-list approach
update-docs-manual.yml	same

Trade-off

Six of the eight workflows previously fetched only a 4-6 submodule selective list (no submodules: true on parent). Adding submodules: true makes the parent shallow-clone all 29 top-level submodules at depth 1 — the heavy ones (openvdb, GDCM, libE57Format, mbedtls, onetbb, opencascade-related) are now fetched even though the docker image already provides them pre-built. With depth 1 over GitHub's fast remote this adds an estimated 20–50 s per matrix leg, and is paid in parallel with other parts of the checkout — small relative to multi-minute build times.

In exchange, the workflow code becomes much easier to reason about: every "Checkout / Checkout mrbind submodules" pair across the repo now does the same thing.

Net diff

+69 / −32 across 8 files, two commits:

• b7e8069c — macos + windows rename only
• 161b3cfa — extend pattern to the other six workflows

🤖 Generated with Claude Code

[Fedr]

Direction reversed — replaced by a fresh PR that takes the opposite approach (selective list across all 8 workflows, no submodules: true anywhere).