fix(install): accept common truthy values for OPENSHELL_NO_VERIFY

- Accept 1, true, yes, y (case-insensitive) for OPENSHELL_NO_VERIFY
- Clean up temp directory in e2e checksum skip test

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Signed-off-by: areporeporepo <areporeporepo@users.noreply.github.com>

Author: areporeporepo

e2e/install/sh_test.sh

@@ -71,13 +71,15 @@ test_guidance_mentions_restart() {
 test_skip_checksum_env() {
   printf 'TEST: OPENSHELL_NO_VERIFY=1 skips checksum verification\n'
 
-  _skip_dir="$(mktemp -d)/bin"
+  _skip_base="$(mktemp -d)"
+  _skip_dir="${_skip_base}/bin"
   _skip_output="$(OPENSHELL_NO_VERIFY=1 \
     OPENSHELL_INSTALL_DIR="$_skip_dir" \
     SHELL="/bin/sh" \
     PATH="/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin" \
     sh "$INSTALL_SCRIPT" 2>&1)" || {
     fail "install succeeds with OPENSHELL_NO_VERIFY=1" "exit code: $?"
+    rm -rf "$_skip_base"
     return 1
   }
 
@@ -89,6 +91,7 @@ test_skip_checksum_env() {
   else
     fail "binary installed with checksum skip" "not found at $_skip_dir/openshell"
   fi
+  rm -rf "$_skip_base"
 }
 
 test_no_env_scripts_created() {

install.sh

@@ -227,7 +227,12 @@ is_on_path() {
 # ---------------------------------------------------------------------------
 
 main() {
-  _skip_checksum="${OPENSHELL_NO_VERIFY:-0}"
+  # Normalise OPENSHELL_NO_VERIFY to "1" or "0".
+  # Accept common truthy values: 1, true, yes, y (case-insensitive).
+  case "$(printf '%s' "${OPENSHELL_NO_VERIFY:-}" | tr '[:upper:]' '[:lower:]')" in
+    1|true|yes|y) _skip_checksum=1 ;;
+    *)            _skip_checksum=0 ;;
+  esac
 
   # Parse CLI flags
   for arg in "$@"; do