Update .gitignore and fix audit paths to use standard Linux directories

- Add comprehensive runtime file patterns to .gitignore (data/, config/, logs/, production/, *.log, *.db, *.db-wal, *.db-shm)
- Keep *.example files tracked for configuration templates
- Update CLI audit command to use FHS-compliant paths (/var/lib/aitbc, /etc/aitbc, /var/log/aitbc)

cli/core/main.py

@@ -50,7 +50,7 @@ def audit():
     click.echo("Service Health: ✅")
     
     # Check repository cleanliness
-    repo_dirs = ['/opt/aitbc/data', '/opt/aitbc/config', '/opt/aitbc/logs']
+    repo_dirs = ['/var/lib/aitbc/data', '/etc/aitbc', '/var/log/aitbc']
     clean = True
     for dir_path in repo_dirs:
         if os.path.exists(dir_path):