chore(root): add mimic directory to gitignore

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

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

Author: gracefullight

.gitignore

@@ -64,3 +64,5 @@ apps/mobile/.packages
 *.bak
 *.tmp
 .cache/
+
+.opencode/mimic/