chore: add changeset for changed keys feature

Author: piotrski

.changeset/surface-changed-keys.md

@@ -0,0 +1,12 @@
+---
+"agent-react-devtools": minor
+---
+
+Surface specific changed prop/state/hook keys in profiling output
+
+Profiling reports and commit details now show *which* props, state keys, and hooks changed, not just *that* they changed.
+
+- `profile report` and `profile slow` append `changed: props: onClick, className  state: count` lines
+- `profile rerenders` and `profile commit` include the same detail per component
+- Keys are deduplicated across commits in aggregate reports
+- Empty keys produce no extra output (backward-compatible)