refactor: rename pass_mgr to secret-mgr

The secret manager binary was renamed from pass_mgr to secret-mgr.
Update all references in CLI code, mode detection, and help text.

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

internal/commands/config.go

@@ -20,7 +20,7 @@ func RunConfigURL(url string) {
 	fmt.Printf("base-url set to %s\n", url)
 }
 
-// RunConfigAccMgrToken stores the account-manager token via pass_mgr.
+// RunConfigAccMgrToken stores the account-manager token via secret-mgr.
 func RunConfigAccMgrToken(token string) {
 	if token == "" {
 		output.Error("usage: hf config --acc-mgr-token <token>")