ci(fresh-install): add findutils to arch/tumbleweed distro legs (#135)

* ci(fresh-install): add findutils to arch/tumbleweed distro legs

quick_install.sh (fetched from xlings main) locates the extracted
xlings dir with `find`. On opensuse/tumbleweed:latest, which ships
without findutils, the install died with:

    bash: line 148: find: command not found
    exit code 127

before mcpp ever ran. The arch leg lacked an explicit findutils too
and only passed because the base image bundles it.

List findutils explicitly on both legs (matching fedora/debian/ubuntu)
and add a matrix note so the hard `find` dependency isn't dropped again.

Failing run: https://github.com/mcpp-community/mcpp/actions/runs/27796803895

* ci(fresh-install): drop redundant GITHUB_PATH append in container leg

The findutils fix unmasked a second, tumbleweed-only failure at the
start of "Configure mcpp":

    OCI runtime exec failed: exec: "sh": executable file not found in $PATH
    exit code 127

opensuse/tumbleweed's image declares no PATH in its config. Appending a
single dir to $GITHUB_PATH makes the runner exec every later step's
`sh` with only that dir on PATH, so /usr/bin/sh becomes unfindable. The
setup/install steps passed only because they ran before the append.

Every container-matrix step already does
`export PATH="$HOME/.xlings/subos/current/bin:$PATH"` in its own
script, so the GITHUB_PATH append was redundant — and the sole cause of
the corruption. Drop it. (The bare linux-fresh leg keeps its
GITHUB_PATH: its later steps call mcpp directly without re-exporting.)

Author: Sunrisepeak

.github/workflows/ci-fresh-install.yml

@@ -136,16 +136,22 @@ jobs:
     strategy:
       fail-fast: false
       matrix:
+        # findutils (find) is mandatory on every leg: quick_install.sh
+        # locates the extracted xlings dir with `find`, so a missing find
+        # fails the install with exit 127 *before* mcpp ever runs. Minimal
+        # images (opensuse/tumbleweed) ship without it; arch's base merely
+        # bundles it by luck. List it explicitly everywhere — don't rely on
+        # the base image.
         include:
           - distro: fedora-latest
             image: fedora:latest
             setup: dnf -y install curl bash tar gzip xz git findutils binutils file glibc-langpack-en
           - distro: arch
             image: archlinux:latest
-            setup: pacman -Sy --noconfirm curl bash tar gzip xz git binutils file
+            setup: pacman -Sy --noconfirm curl bash tar gzip xz git findutils binutils file
           - distro: tumbleweed
             image: opensuse/tumbleweed:latest
-            setup: zypper -n install curl bash tar gzip xz git binutils file
+            setup: zypper -n install curl bash tar gzip xz git findutils binutils file
           - distro: debian-testing
             image: debian:testing
             setup: apt-get update && apt-get -y install curl bash tar gzip xz-utils git ca-certificates binutils findutils file
@@ -167,7 +173,13 @@ jobs:
       - name: Install xlings + mcpp
         run: |
           curl -fsSL https://raw.githubusercontent.com/openxlings/xlings/main/tools/other/quick_install.sh | bash -s v0.4.38
-          echo "$HOME/.xlings/subos/current/bin" >> "$GITHUB_PATH"
+          # Deliberately NOT writing to $GITHUB_PATH here. On container
+          # images that declare no PATH in their config (opensuse/
+          # tumbleweed), appending a single dir to GITHUB_PATH makes the
+          # runner exec later steps' `sh` with only that dir on PATH —
+          # `sh` (in /usr/bin) vanishes and the next step dies with
+          # `exec: "sh": ... not found` / exit 127. Each step below already
+          # exports PATH itself, so the append is redundant anyway.
 
       - name: Configure mcpp
         run: |