chore: Ignore the .adk/ directory

Co-authored-by: George Weale <[email protected]>
PiperOrigin-RevId: 840387909

Author: GWeale

.gitignore

@@ -101,6 +101,7 @@ Thumbs.db
 
 # AI Coding Tools - Project-specific configs
 # Developers should symlink or copy AGENTS.md and add their own overrides locally
+.adk/
 .claude/
 CLAUDE.md
 .cursor/