Prove the migration against live directories and fix what that surfaced

Finishes the unproven half of gap G04. Running the harness against real LLDAP,
OpenLDAP and Keycloak found four defects that the full unit suite passed over.

Every LLDAP user search pointed at a branch that does not exist. Config.userOU()
defaulted to ou=users while LLDAP stores users under ou=people, and nothing set
UserOU. LookupUser, ListUsers and ValidatePassword all derive from it, so all
three silently found nothing against a stock LLDAP -- human login included, not
only the export. Exposed by an export returning zero users while still emitting a
membership referencing uid=admin, a snapshot the repo's own validator rejects.

raw_attributes_well_formed, added one workplan earlier, rejected the LLDAP
adapter's own _validation_warning annotation, so the exporter's output failed its
own validation. Tooling annotations are exempt now, and a test proves the
exemption does not weaken the rule.

Migrated group memberships were dangling: resolveMemberDN passed a source DN
through unchanged while entries were written to the target branch, so groups
named entries the migrated directory does not contain. And empty groups could
not load at all, since groupOfNames makes member a MUST -- they reference a
placeholder entry the LDIF creates, an organizationalRole rather than a person,
emitted only when some group needs it.

The scenario-c compose file could not start: bitnami/openldap:2.6 does not
exist, though it passed docker compose config. Pinned to the image the scenario
was proved against.

Proof: LLDAP -> export -> validate -> LDIF -> ldapadd into OpenLDAP 1.5.0, every
entry added and every member resolving; a realm from the same export imports into
Keycloak and serves discovery. KeyCape passes 5/5 conformance checks, a migrated
Keycloak 4/5.

Relying-party behaviour and MFA against a migrated realm remain unexercised, and
credential/MFA migration is not supplied at all, so no harness can establish it.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01NV9oijZukGyGbRQGGKnK4P

Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 713576@bnt-lap001
Assistant-Session: 384c511d-9bce-4cb8-a676-2aef6c0c8df6

src/internal/validator/validator.go

@@ -117,6 +117,14 @@ func checkRawAttributesWellFormed(snap Snapshot) RuleResult {
 		// only by case are one attribute supplied twice, not two attributes.
 		seen := make(map[string]string, len(u.LDAPAttributes))
 		for key := range u.LDAPAttributes {
+			// Keys beginning with "_" are annotations this tooling writes into
+			// the snapshot itself -- the LLDAP adapter records
+			// "_validation_warning" here, for one. They are not directory
+			// attributes and must not be judged as though they were, or the
+			// exporter's own output fails validation (KEY-WP-0023).
+			if strings.HasPrefix(key, "_") {
+				continue
+			}
 			switch {
 			case strings.TrimSpace(key) == "":
 				r.Passed = false

src/internal/validator/validator_test.go

@@ -371,3 +371,24 @@ func findRule(results []validator.RuleResult, name string) validator.RuleResult
 	}
 	return validator.RuleResult{Rule: name, Passed: false, Message: "rule not found in report"}
 }
+
+// The LLDAP adapter records "_validation_warning" in LDAPAttributes, so the rule
+// must not judge the tooling's own annotations as directory attributes. Found by
+// validating a snapshot exported from a live LLDAP (KEY-WP-0023).
+func TestRawAttributes_IgnoresToolingAnnotations(t *testing.T) {
+	result := attributeRule(t, map[string]string{
+		"_validation_warning": "required_attributes_present: missing displayName",
+		"sn":                  "Example",
+	})
+	if !result.Passed {
+		t.Errorf("tooling annotation rejected: %s", result.Message)
+	}
+}
+
+// The exemption is for annotations only: a real attribute is still judged.
+func TestRawAttributes_ExemptionDoesNotWeakenTheRule(t *testing.T) {
+	result := attributeRule(t, map[string]string{"_note": "fine", "employee_id": "42"})
+	if result.Passed {
+		t.Error("expected the malformed real attribute to still fail")
+	}
+}