refactor: centralize strict numeric parsing

src/cli/shared/parse-port.ts

@@ -1,19 +1,8 @@
+import { parseStrictPositiveInteger } from "../../infra/parse-finite-number.js";
+
 export function parsePort(raw: unknown): number | null {
   if (raw === undefined || raw === null) {
     return null;
   }
-  const value =
-    typeof raw === "string"
-      ? raw
-      : typeof raw === "number" || typeof raw === "bigint"
-        ? raw.toString()
-        : null;
-  if (value === null) {
-    return null;
-  }
-  const parsed = Number.parseInt(value, 10);
-  if (!Number.isFinite(parsed) || parsed <= 0) {
-    return null;
-  }
-  return parsed;
+  return parseStrictPositiveInteger(raw) ?? null;
 }