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/tui/native/linux/README.md

@@ -0,0 +1,23 @@
+# Linux clipboard helper
+
+Provides asynchronous X11 text and image reads using `libxcb.so.1`. Prebuilds support x64 and arm64 on glibc and musl. Reads have bounded waits; if a native operation stalls, the helper remains unavailable until it finishes.
+
+Coding-agent falls back to command-line tools when native reads are unavailable. Wayland reads use `wl-paste`; all Linux writes use the existing command-line or terminal clipboard paths.
+
+## Building
+
+Install a C compiler and XCB development headers, then run from the repository root on each supported Linux architecture:
+
+```sh
+npm --prefix packages/tui run build:native:linux
+```
+
+## Testing
+
+Install the build dependencies plus `pkg-config`, `Xvfb`, and `xclip`, then run from `packages/tui`:
+
+```sh
+node --test test/native-clipboard-linux.test.ts
+```
+
+Tests use isolated X11 servers, not the desktop clipboard. They skip when dependencies are missing.