feat(browser): add browser build, tests, and sample sha256 library method

src/lib/hash.ts

@@ -0,0 +1,17 @@
+import { createHash } from 'crypto'
+
+/**
+ * Calculate the sha256 digest of a string. On Node.js, this will use the native module, in the browser, it will fall back to a pure javascript implementation.
+ *
+ * ### Example (es imports)
+ * ```js
+ * import { sha256 } from 'typescript-starter'
+ * sha256('test')
+ * // => '9f86d081884c7d659a2feaa0c55ad015a3bf4f1b2b0b822cd15d6c15b0f00a08'
+ * ```
+ *
+ * @returns sha256 message digest
+ */
+export function sha256 (message: string) {
+  return createHash('sha256').update(message).digest('hex')
+}