Quote mise-install arguments and refuse unusable command names

The wrapper is written through an unquoted heredoc, so the package and bin
names land in it as shell source. A package name carrying shell characters
became code that ran every time the wrapper ran.

The command name is used raw as a file name under ~/.local/bin, so a slash in
it wrote and removed somewhere else entirely.

Quote both values with printf %q, and refuse command names that are not plain
file names before anything is removed or written.

test/shell.d/mise-install-test.sh

@@ -0,0 +1,84 @@
+#!/bin/bash
+
+set -euo pipefail
+
+source "$(dirname "${BASH_SOURCE[0]}")/base-test.sh"
+
+tmpdir=$(mktemp -d)
+trap 'rm -rf "$tmpdir"' EXIT
+
+home="$tmpdir/home"
+stub_bin="$tmpdir/bin"
+mkdir -p "$home" "$stub_bin"
+
+# Stands in for the real mise so a generated wrapper can be run and asked what
+# arguments it passed on.
+cat >"$stub_bin/mise" <<'SH'
+#!/bin/bash
+
+printf 'mise' >>"$OMARCHY_MISE_TEST_LOG"
+for arg in "$@"; do
+  printf '\t%s' "$arg" >>"$OMARCHY_MISE_TEST_LOG"
+done
+printf '\n' >>"$OMARCHY_MISE_TEST_LOG"
+SH
+chmod +x "$stub_bin/mise"
+
+install_wrapper() {
+  HOME="$home" "$ROOT/bin/omarchy-mise-install" "$@"
+}
+
+# The ordinary case still works, and every call site in install/user/mise.sh
+# passes names of this shape.
+install_wrapper npm:playwright playwright >/dev/null
+[[ -x $home/.local/bin/playwright ]] ||
+  fail "a normal install writes an executable wrapper"
+
+log="$tmpdir/normal.log"
+: >"$log"
+OMARCHY_MISE_TEST_LOG="$log" PATH="$stub_bin:$PATH" "$home/.local/bin/playwright" >/dev/null
+grep -Fqx $'mise\tuse\t-g\t--quiet\tnpm:playwright' "$log" ||
+  fail "the wrapper asks mise for the package it was given" "$(cat "$log")"
+
+pass "a normal install writes a wrapper that names its package"
+
+# A package name is data. Quoted with %q it reaches mise as one argument
+# instead of being read as shell source when the wrapper runs.
+install_wrapper 'npm:pkg$(touch '"$tmpdir"'/PWNED)end' hostile >/dev/null
+
+log="$tmpdir/hostile.log"
+: >"$log"
+OMARCHY_MISE_TEST_LOG="$log" PATH="$stub_bin:$PATH" "$home/.local/bin/hostile" >/dev/null
+
+[[ -e $tmpdir/PWNED ]] &&
+  fail "a package name with shell characters does not run when the wrapper does" \
+    "wrapper: $(cat "$home/.local/bin/hostile")"
+
+grep -Fqx $'mise\tuse\t-g\t--quiet\tnpm:pkg$(touch '"$tmpdir"'/PWNED)end' "$log" ||
+  fail "the package reaches mise whole" "$(cat "$log")"
+
+pass "a package name with shell characters reaches mise as one argument"
+
+# The command name is a file name under ~/.local/bin. These shapes escape it,
+# hide it, or make something that reads as an option.
+for name in ../escaped .hidden -dash; do
+  if install_wrapper somepkg "$name" >/dev/null 2>"$tmpdir/err"; then
+    fail "a command name of '$name' is refused"
+  fi
+  grep -Fq 'is not usable as a command name' "$tmpdir/err" ||
+    fail "the refusal says why for '$name'" "$(cat "$tmpdir/err")"
+done
+
+pass "command names that are not plain file names are refused"
+
+# The refusal has to land before the rm, which would otherwise delete the
+# escaped path on its way to failing.
+victim="$tmpdir/victim"
+printf 'keep me\n' >"$victim"
+if install_wrapper somepkg "../../../..$victim" >/dev/null 2>&1; then
+  fail "an escaping command name is refused"
+fi
+[[ -f $victim ]] ||
+  fail "an escaping command name removes nothing outside ~/.local/bin"
+
+pass "an escaping command name removes nothing outside ~/.local/bin"