fix: allowlist historical commit in gitleaks config

Commit 2fdb5ba introduced functional_test.go with an example API key
value in a doc comment (for illustrating how to run the test). It was
not a real credential and has since been replaced with <YOUR_API_KEY>
placeholder, but gitleaks scans the full commit history so the original
commit still triggers the rule. Allowlist the commit SHA explicitly.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: sarg3nt

.gitleaks.toml

@@ -71,7 +71,11 @@ regexes = [
 ]
 
 # Allowlist - commits to ignore
-commits = []
+# 2fdb5ba: functional_test.go had an example API key value in a doc comment
+# (test-only, not a real credential — replaced with <YOUR_API_KEY> placeholder in a later commit)
+commits = [
+    "2fdb5ba0d2e8da23a6409527cdbf6696d90eb537",
+]
 
 # Stopwords - tokens that if found will stop gitleaks
 stopwords = [