Rename strutil to stringsx, use wg.Go

Address PR review feedback: rename the shared string-helper package
from strutil to stringsx to avoid the discouraged util suffix and the
collision with the standard strings package, updating all import paths
and call sites.

Replace the manual wg.Add/wg.Done bookkeeping in the enrichment worker
with wg.Go, which is less error-prone.

Signed-off-by: Émile Ré <emile@probo.com>

pkg/stringsx/stringsx.go

@@ -0,0 +1,35 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+// Package stringsx holds small, dependency-free string helpers shared
+// across packages.
+package stringsx
+
+import "strings"
+
+// NormalizeAlnum lowercases s and keeps only ASCII letters and digits, so
+// vendor names and domains can be compared free of spacing, punctuation,
+// and casing differences (e.g. "Letaido" and "letaido.com" both reduce to
+// a comparable form).
+func NormalizeAlnum(s string) string {
+	var b strings.Builder
+
+	for _, r := range strings.ToLower(s) {
+		if (r >= 'a' && r <= 'z') || (r >= '0' && r <= '9') {
+			b.WriteRune(r)
+		}
+	}
+
+	return b.String()
+}

pkg/stringsx/stringsx_test.go

@@ -0,0 +1,48 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package stringsx_test
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"go.probo.inc/probo/pkg/stringsx"
+)
+
+func TestNormalizeAlnum(t *testing.T) {
+	t.Parallel()
+
+	tests := []struct {
+		name     string
+		input    string
+		expected string
+	}{
+		{name: "letters lowercased", input: "Letaido", expected: "letaido"},
+		{name: "strips punctuation and spaces", input: "letaido.com - Inc", expected: "letaidocominc"},
+		{name: "keeps digits", input: "auth0", expected: "auth0"},
+		{name: "empty", input: "", expected: ""},
+		{name: "only punctuation", input: "-_.:", expected: ""},
+	}
+
+	for _, tt := range tests {
+		t.Run(
+			tt.name,
+			func(t *testing.T) {
+				t.Parallel()
+				assert.Equal(t, tt.expected, stringsx.NormalizeAlnum(tt.input))
+			},
+		)
+	}
+}