feat: M2 database migration runner with Phinx and initial schema

docker/README.md

@@ -53,8 +53,8 @@ independent of your current working directory and propagate exit codes.
 ./dev.sh lint        # run composer lint inside the app container
 ./dev.sh assets      # build minified CSS inside the assets container
 ./dev.sh watch       # start Tailwind watch inside the assets container
-./dev.sh migrate     # unavailable until M2 (#12); exits nonzero
-./dev.sh seed        # unavailable until M2 (#12); exits nonzero
+./dev.sh migrate     # run database migrations (M2 #12)
+./dev.sh seed        # seed default reference data (M2 #12)
 ```
 
 `down --volumes` and `down -v` are blocked by the wrapper. Never remove the named