dockerimg: add 'apk add grep'

Claude wants to use lots of grep features that the busybox version lacks.

Co-Authored-By: sketch <hello@sketch.dev>
diff --git a/dockerimg/createdockerfile.go b/dockerimg/createdockerfile.go
index 56bab5d..7971d38 100644
--- a/dockerimg/createdockerfile.go
+++ b/dockerimg/createdockerfile.go
@@ -47,7 +47,7 @@
 // If/when we do this, add them into the list of available tools in bash.go.
 const dockerfileBaseTmpl = `FROM {{.From}}
 
-RUN apk add bash git make jq sqlite gcc musl-dev linux-headers npm nodejs go github-cli ripgrep fzf python3 curl vim
+RUN apk add bash git make jq sqlite gcc musl-dev linux-headers npm nodejs go github-cli ripgrep fzf python3 curl vim grep
 
 ENV GOTOOLCHAIN=auto
 ENV GOPATH=/go