feat(worker): add logout + replace admin-only settings with Account screen

The Instellingen tab was activity management, which Phase 2 made admin-only —
workers saw add/edit/delete controls that all 403. Replace it with an Account
tab showing the signed-in name/email (via /api/me) and an Uitloggen button
(wires the existing AuthContext signOut). Activity management belongs to the
Phase 3 admin app, so the worker client drops the Settings screen and its
now-unused activity-mutation hooks (useActivities read stays).

Products affected: SoleLog worker client (apps/worker).

apps/worker/src/styles.css

@@ -274,6 +274,33 @@ body {
   cursor: pointer;
 }
 
+/* ---- Account ---- */
+.account-card {
+  gap: 4px;
+}
+
+.account-name {
+  font-size: 18px;
+  font-weight: 600;
+}
+
+.account-email {
+  color: var(--text-muted);
+  font-size: 15px;
+}
+
+.btn-logout {
+  width: 100%;
+  padding: 16px;
+  font-size: 16px;
+  font-weight: 600;
+  color: var(--danger);
+  background: #ffffff;
+  border: 1px solid var(--danger);
+  border-radius: 16px;
+  cursor: pointer;
+}
+
 /* ---- History (Geschiedenis) ---- */
 .history-header {
   display: flex;