chore: add change files for PR1 strict-mode/lifecycle refactor

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: bsunderhus

change/@fluentui-priority-overflow-pr1-strict-mode.json

@@ -0,0 +1,7 @@
+{
+  "type": "minor",
+  "comment": "feat: createOverflowManager accepts initialOptions, new setOptions method, observe now returns its cleanup, and the OverflowManagerOptions type is exported.",
+  "packageName": "@fluentui/priority-overflow",
+  "email": "bsunderhus@microsoft.com",
+  "dependentChangeType": "patch"
+}

change/@fluentui-react-overflow-pr1-strict-mode.json

@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "fix: make Overflow container strict-mode safe by creating the manager via useMemo, starting observation in a single layout effect with colocated cleanup, propagating option changes through setOptions, and ref-guarding overflow menu and divider deregistration.",
+  "packageName": "@fluentui/react-overflow",
+  "email": "bsunderhus@microsoft.com",
+  "dependentChangeType": "patch"
+}