fix: v0.2.3 e2e distro loop, FIDO2 freeze, grouped prompts

Fix e2e.sh distro iteration broken by IFS setting (use bash array).
Fix FIDO2 detection freezing on macOS (check ssh-sk-helper, don't
invoke ssh-keygen). Group apply prompts into 6 categories. Fix Linux
gitleaks install hint.

Co-Authored-By: Claude <noreply@anthropic.com>

test/git-harden.bats

@@ -1148,7 +1148,7 @@ EOF
 # v0.2.0: Version bump
 # ===========================================================================
 
-@test "--version reports 0.2.2" {
+@test "--version reports 0.2.3" {
     run bash "$SCRIPT" --version
-    assert_output --partial "0.2.2"
+    assert_output --partial "0.2.3"
 }