chore: add .codegraph/.gitignore

Ignore local CodeGraph artifacts (db, logs, sockets) while tracking the .gitignore itself.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

.codegraph/.gitignore

@@ -0,0 +1,5 @@
+# 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