ci: opt into integration/e2e tiers + README template badges

Follow-up to the go-check.yml integration/e2e expansion in
netresearch/.github. This repo has integration/e2e test files so
enable the corresponding go-check inputs, and add the drift-check +
template-source badges to the README so template governance is
visible on the repo landing page.

Signed-off-by: Sebastian Mendel <sebastian.mendel@netresearch.de>

Author: CybotTM

README.md

@@ -1,5 +1,8 @@
 # Raybeam
 
+[![Template Drift](https://github.com/netresearch/raybeam/actions/workflows/check-template-drift.yml/badge.svg)](https://github.com/netresearch/raybeam/actions/workflows/check-template-drift.yml)
+[![managed by netresearch/.github templates](https://img.shields.io/badge/template-netresearch%2F.github-2F99A4?logo=github)](https://github.com/netresearch/.github/tree/main/templates/go-app)
+
 [![Go Reference](https://pkg.go.dev/badge/github.com/netresearch/raybeam.svg)](https://pkg.go.dev/github.com/netresearch/raybeam)
 [![Go Report Card](https://goreportcard.com/badge/github.com/netresearch/raybeam)](https://goreportcard.com/report/github.com/netresearch/raybeam)
 [![CI Status](https://github.com/netresearch/raybeam/actions/workflows/ci.yml/badge.svg)](https://github.com/netresearch/raybeam/actions/workflows/ci.yml)