Merge feature/ticket79-flaky-permissions-test into develop

Ticket #79 : fix du flake PermissionsPanel > saves project defaults
(PermissionEditor draft resync clobbering in-flight edits). QA vert sur le
périmètre du ticket (2/2 stable + suite complète non-shuffled) ; le rouge
observé en shuffle vient d'un autre test préexistant sans rapport
(setCellAgent.test.tsx, tracé séparément en #85).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/src/features/permissions/PermissionsPanel.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useMemo, useState } from "react";
+import { useEffect, useMemo, useRef, useState } from "react";
 
 import { Button, Panel, Spinner, cn } from "@/shared";
 import type { PermissionSet, PermissionPosture } from "@/domain";
@@ -232,9 +232,26 @@ function PermissionEditor({
   onClear,
 }: PermissionEditorProps) {
   const [local, setLocal] = useState<PolicyDraft>(draft);
-
+  // `draft` is a NEW object every time the underlying document changes for ANY
+  // reason (initial load landing after mount, a Refresh, another tab's save…),
+  // even when its content matches what is already in `local`. Naively
+  // re-syncing on every `draft` change is a genuine race: if it fires after the
+  // user has started editing (in production: a slow initial fetch landing
+  // right as the user types; in tests: a passive effect flushing later than a
+  // synchronous `fireEvent` sequence — ticket #79 flake), it silently discards
+  // the user's in-progress edit. `prevDraftRef` tracks the last draft this
+  // effect adopted `local` from; we only re-sync when `local` still matches it
+  // (nothing has been edited since), so a legitimate incoming draft (first
+  // load, or the echo of the user's own just-saved edit) is adopted, but an
+  // edit in flight never gets clobbered.
+  const prevDraftRef = useRef(draft);
   useEffect(() => {
-    setLocal(draft);
+    setLocal((current) =>
+      JSON.stringify(current) === JSON.stringify(prevDraftRef.current)
+        ? draft
+        : current,
+    );
+    prevDraftRef.current = draft;
   }, [draft]);
 
   const changed = useMemo(