docs(16): close Phase 16 UAT with A1 accepted as an open assumption

The user has no write access to the company AD, so tests 1, 3, 4 and 8 cannot
be run there, and building a throwaway domain controller for them was judged
disproportionate now that the one substantive defect at this spot is found and
fixed (UAT test 2 -> quick task 260811-f9i).

Recorded rather than hidden: A1 (objectGUID survives a rename) now rests on
Microsoft's documentation, not on our own measurement. The Tessera-side rename
and delete logic stays covered by unit tests against fixtures. If a rename ever
fails to propagate in production, 16-VERIFICATION.md names that as the starting
point.

Phase 16 marked complete in STATE.md.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

.planning/STATE.md

@@ -4,14 +4,14 @@ milestone: v1.1
 milestone_name: Ausschreibungs-Radar
 current_phase: 16
 current_phase_name: AD-Gruppen-Synchronisation
-status: verifying
-stopped_at: Completed 16-05-PLAN.md — Phase 16 complete (5/5), PERM-02 closed
-last_updated: "2026-08-06T14:41:05.149Z"
-last_activity: 2026-08-06
-last_activity_desc: Phase 16 execution started
+status: complete
+stopped_at: Phase 16 abgeschlossen — UAT durchgefuehrt, kritischer Sweep-Fehler gefunden und behoben (260811-f9i), Rest-Annahme A1 bewusst als offen akzeptiert
+last_updated: "2026-08-11T09:25:00.000Z"
+last_activity: 2026-08-11
+last_activity_desc: Phase 16 UAT abgeschlossen; objectGUID-Existenzpruefung repariert
 progress:
   total_phases: 16
-  completed_phases: 14
+  completed_phases: 15
   total_plans: 80
   completed_plans: 78
 ---
@@ -27,12 +27,17 @@ See: .planning/PROJECT.md (updated 2026-07-17)
 
 ## Current Position
 
-Phase: 16 (AD-Gruppen-Synchronisation) — EXECUTING
+Phase: 16 (AD-Gruppen-Synchronisation) — COMPLETE
 Plan: 5 of 5
-Status: Phase complete — ready for verification
-Last activity: 2026-08-06 — Phase 16 execution started
+Status: Abgeschlossen. UAT 2/5/6 bestanden, 7 teilweise, 1/3/4/8 bewusst
+uebersprungen (kein AD-Schreibzugriff, Entscheidung des Users 2026-08-11).
+UAT-Test 2 hat einen kritischen Fehler in der Loescherkennung aufgedeckt, der
+beim ersten echten Sync alle AD-gebundenen Gruppen entfernt haette — behoben in
+260811-f9i. Offene Annahme A1 (objectGUID uebersteht Umbenennung) steht
+dokumentiert in 16-VERIFICATION.md.
+Last activity: 2026-08-11 — UAT abgeschlossen, Sweep-Fix ausgeliefert
 
-Progress: [██████████] 98%
+Progress: [██████████] 100%
 
 ## Performance Metrics
 
@@ -317,7 +322,7 @@ Items acknowledged and carried forward from previous milestone close:
 
 ## Session Continuity
 
-Last session: 2026-08-06T14:41:05.118Z
-Stopped at: Completed 16-05-PLAN.md — Phase 16 complete (5/5), PERM-02 closed
+Last session: 2026-08-11T09:25:00.000Z
+Stopped at: Phase 16 abgeschlossen — UAT durchgefuehrt, objectGUID-Sweep repariert und gepusht
 Resume file: None
 Last activity: 2026-07-14 - Built LDAP per-user exclude/denylist filter (9d1323f), migration applied on live DB, verified via Playwright: sync deactivated 4 excluded service accounts (administrator/krbtgt/guest/dns-ldap), 2 real LDAP users stay active, 0 wrongly created