feat: add bats tests, docs (#139)

* fix(test): ensure bats file list uses xargs

* docs(readme): use yarn for testing instructions

* fix(test): ensure pipelines fail properly

* docs(alias): fix table header

---------

Signed-off-by: Ismo Vuorinen <ismo@ivuorinen.net>

local/bin/iterm2_shell_integration.zsh.md

@@ -0,0 +1,15 @@
+# iterm2_shell_integration.zsh
+
+Official iTerm2 shell integration script for zsh. Source this file to
+enable prompt tracking and command notifications in iTerm2.
+
+## Usage
+
+```bash
+source iterm2_shell_integration.zsh
+```
+
+No parameters are required. The script modifies your prompt to work
+with iTerm2 features such as badges and profile switching.
+
+<!-- vim: set ft=markdown spell spelllang=en_us cc=80 : -->