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/docs/shell-aliases.md

@@ -0,0 +1,13 @@
+# Shell Aliases
+
+Pi runs bash in non-interactive mode (`bash -c`), which doesn't expand aliases by default.
+
+To enable your shell aliases, add to `~/.pi/agent/settings.json`:
+
+```json
+{
+  "shellCommandPrefix": "shopt -s expand_aliases\neval \"$(grep '^alias ' ~/.zshrc)\""
+}
+```
+
+Adjust the path (`~/.zshrc`, `~/.bashrc`, etc.) to match your shell config.