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/x-backup-mysql-with-prefix.md

@@ -0,0 +1,21 @@
+# x-backup-mysql-with-prefix
+
+Dump MySQL tables matching a prefix to a timestamped file.
+
+## Usage
+
+```bash
+x-backup-mysql-with-prefix <prefix> <name> [database]
+```
+
+- `prefix` – table prefix to match (e.g. `wp_`)
+- `name` – file name prefix
+- `database` – database name (default: `wordpress`)
+
+## Example
+
+```bash
+x-backup-mysql-with-prefix wp_ blog
+```
+
+<!-- vim: set ft=markdown spell spelllang=en_us cc=80 : -->