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/streaming-render-debug.ts

@@ -1,7 +1,7 @@
 /**
  * Debug script to reproduce streaming rendering issues.
  * Uses real fixture data that caused the bug.
- * Run with: npx tsx test/streaming-render-debug.ts
+ * Run with: node --import ./src/experimental/source-resolver.ts test/streaming-render-debug.ts
  */
 
 import type { AssistantMessage } from "@earendil-works/pi-ai";