chore(gitignore): ignore built binary and .security-reviewed marker

Le commit precedent a accidentellement inclus le binaire compile et le
marker de security review. Ces fichiers ne doivent jamais etre versionnes.

.gitignore

@@ -5,6 +5,10 @@ dist/
 *.exe
 *.test
 *.out
+/claude-failover
+
+# Security review marker (Claude Code hook, expires after 10min)
+.security-reviewed
 
 # Go
 vendor/