docs: add examples in manifest module

src/manifest.ts

@@ -1,5 +1,15 @@
 import fs from "node:fs";
 
+/**
+ * Writes manifest entries as newline-delimited, sorted values.
+ *
+ * @param filePath Output manifest path.
+ * @param entries Manifest entries to normalize and write.
+ * @returns Nothing.
+ *
+ * @example
+ * writeManifest("/tmp/manifest.log", ["git=2.39", "curl=8.5.0"]);
+ */
 export function writeManifest(filePath: string, entries: string[]): void {
   const normalized = [...entries]
     .filter(Boolean)
@@ -7,6 +17,15 @@ export function writeManifest(filePath: string, entries: string[]): void {
   fs.writeFileSync(filePath, normalized.join("\n"), "utf8");
 }
 
+/**
+ * Reads a newline-delimited manifest and returns a CSV string.
+ *
+ * @param filePath Input manifest path.
+ * @returns Comma-separated manifest entries or an empty string when missing.
+ *
+ * @example
+ * const csv = readManifestAsCsv("/tmp/manifest.log");
+ */
 export function readManifestAsCsv(filePath: string): string {
   if (!fs.existsSync(filePath)) {
     return "";