chore: update .gitignore file

.codegraph/.gitignore

@@ -1,17 +1,5 @@
-# CodeGraph data files
-# These are local to each machine and should not be committed
-
-# Database
-*.db
-*.db-wal
-*.db-shm
-
-# Cache
-cache/
-
-# Logs
-*.log
-
-# Hook markers
-.dirty
-*.pid
+# CodeGraph data files — local to each machine, not for committing.
+# Ignore everything in .codegraph/ except this file itself, so transient
+# files (the database, daemon.pid, sockets, logs) never show up in git.
+*
+!.gitignore