chore(kb): add memory/kb to git tracking

memory/* was fully ignored; now only memory/kb/ is tracked
so notes, coaching sessions, insights, and project docs are
versioned while embeddings and sqlite databases stay untracked.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

memory/kb/retete/.rules.json

@@ -0,0 +1,5 @@
+{
+  "defaultDomains": ["health"],
+  "defaultTypes": [],
+  "defaultTags": []
+}