Add rush change file for exit-code semantics

Assistant-model: GitHub Copilot
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Copilot-Session: 897dcf7e-e6e8-4a84-85ca-34b93fa29be3

Author: TheLarkInn

common/changes/@rushstack/reporter/docs-rush-reporter-overhaul-spec_2026-07-15-00-35-03.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "@rushstack/reporter",
+      "comment": "Add reporter-independent exit-code semantics (resolveExitStatus, resolveExitStatusFromEvents, getSignalExitCode) and separateJsonControls to keep command-specific --json distinct from the json reporter",
+      "type": "minor"
+    }
+  ],
+  "packageName": "@rushstack/reporter",
+  "email": "TheLarkInn@users.noreply.github.com"
+}