fix: add missing cmd/ (gitignore was excluding source dirs)

The initial commit's .gitignore had unanchored 'encapi' and 'encapi-cli'
patterns intended for built binaries; they also matched the cmd/encapi and
cmd/encapi-cli source directories, so those were silently never committed. The
tag build then failed with 'stat /build/cmd/encapi: directory not found'.

- anchor the binary ignores to the repo root (/encapi, /encapi-cli)
- add the cmd/encapi (server) and cmd/encapi-cli (CLI) main packages

cmd/encapi-cli/main.go

@@ -0,0 +1,13 @@
+// Command encapi-cli manages the Puppet ENC via the encapi HTTP API. Puppet's
+// exec node_terminus calls `encapi-cli classify <certname>`.
+package main
+
+import (
+	"os"
+
+	"git.unkin.net/unkin/encapi/internal/cli"
+)
+
+func main() {
+	os.Exit(cli.Run(os.Args[1:], cli.LoadEnv(), os.Stdout, os.Stderr))
+}