chore(vendor): import pi 1.3.0

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: 71023aec1546d6d677a65669c5665c0927ce0dd0

third_party/pi/packages/coding-agent/test/branch-summary-extensions.test.ts

@@ -44,6 +44,7 @@ describe("Branch summary extensions", () => {
 		const summaryEntry = result.summaryEntry;
 
 		expect(summaryEntry?.type).toBe("branch_summary");
+		// The target is the root entry, so the summary attaches to the root's parent.
 		expect(summaryEntry?.parentId).toBeNull();
 		expect(summaryEntry?.fromId).toBe(sourceId);
 		expect(summaryEntry?.fromHook).toBe(true);