fix(sync): bump updated_at on set-icon + folder-delete reassignment

Both UPDATEs mutated a synced column without touching updated_at, so the
change rode in the sync snapshot but other devices skipped it (last-write-
wins saw "not newer"). Now both SET updated_at = datetime('now') (UTC).

- POST /entries/{id}/icon (PM.Handler.Entries)
- folder delete → entries reassigned to 'All' (PM.Handler.Folders)

accessed_at stays exempt (read timestamp, not synced); bulk "clear all
icons" stays exempt (device-local favicon cache purge). Invariant documented
in CLAUDE.md.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

CLAUDE.md

@@ -868,6 +868,14 @@ le vide ET vide `FPendingURL` → écran noir permanent sur cold-start lent.
   nécessite `AttachThreadInput` pour cross-process.
 - **`updated_at`** est bumpé à chaque PUT entry → sort par défaut =
   `name` asc pour que modifier une entry ne change pas sa position.
+- **Toute mutation `vault_entries` qui doit se synchroniser DOIT bumper
+  `updated_at`** : la sync est last-write-wins sur `updated_at`, donc un
+  `UPDATE` qui ne le touche pas voyage bien dans le snapshot mais est ignoré
+  par les autres devices (« pas plus récent »). Corrigé pour set-icône
+  (`POST /entries/{id}/icon`) et réassignation-sur-delete-folder
+  (`PM.Handler.Folders`). `accessed_at` est **exempté** exprès (timestamp de
+  lecture, non synced). Le bulk « clear all icons » ne bump pas non plus —
+  assumé device-local (purge de cache favicon).
 - **Timestamps = UTC partout** : tout `created_at`/`updated_at`/`deleted_at`
   écrit côté Delphi passe par `NowUTC`/`NowUTCStr` (`PM.Database`) — JAMAIS
   `FormatDateTime(..., Now)` (heure locale). SQLite `CURRENT_TIMESTAMP` /

delphi-backend/Handlers/PM.Handler.Entries.pas

@@ -883,7 +883,10 @@ begin
     try
       LQ.Connection := DB.Connection;
       LQ.SQL.Text :=
-        'UPDATE vault_entries SET icon_b64 = :ic ' +
+        // Bump updated_at (UTC) so the icon change wins last-write-wins on
+        // sync — without it the new icon_b64 rides in the snapshot but other
+        // devices skip it (timestamp unchanged → "not newer").
+        'UPDATE vault_entries SET icon_b64 = :ic, updated_at = datetime(''now'') ' +
         'WHERE id=:id AND user_id=:uid';
       LQ.ParamByName('ic').DataType := ftMemo;  // long text → ftMemo on SQLite
       if LIcon = '' then LQ.ParamByName('ic').Clear

delphi-backend/Handlers/PM.Handler.Folders.pas

@@ -350,7 +350,10 @@ begin
     try
       LQ.Connection := DB.Connection;
       LQ.SQL.Text :=
-        'UPDATE vault_entries SET folder = ''All'' ' +
+        // Bump updated_at (UTC) so the folder reassignment propagates on sync
+        // (last-write-wins) — otherwise other devices keep the entries in the
+        // just-deleted folder because the timestamp didn't move.
+        'UPDATE vault_entries SET folder = ''All'', updated_at = datetime(''now'') ' +
         'WHERE user_id = :uid AND folder = :name';
       LQ.ParamByName('uid').AsInteger := LUserId;
       LQ.ParamByName('name').AsString := LName;