chore(vendor): import pi 0.85.1

Imported as a linear vendor commit so forge rebases do not replay the upstream root tree.

git-subtree-dir: third_party/pi

git-subtree-split: d981de1229ef899957bbe968bc8dcda02a21f477

third_party/pi/packages/coding-agent/src/utils/text.ts

@@ -0,0 +1,9 @@
+/** Split a leading UTF-8 byte order mark from decoded text. */
+export function splitBom(content: string): { bom: string; text: string } {
+	return content.startsWith("\uFEFF") ? { bom: "\uFEFF", text: content.slice(1) } : { bom: "", text: content };
+}
+
+/** Remove a leading UTF-8 byte order mark from decoded text. */
+export function stripBom(content: string): string {
+	return splitBom(content).text;
+}