Add OpenTofu module for GitHub repo guard-rails

Manages branch protection ruleset and deployment environments for this
repository. Mirrored to JMR-dev/gh-repo-bootstrap as a reusable module
+ gh CLI extension.

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

infra/github/backend.hcl.example

@@ -0,0 +1,8 @@
+# Example Cloudflare R2 backend configuration.
+# Copy to `backend.hcl` (gitignored) and fill in your values, then run:
+#   tofu init -backend-config=backend.hcl
+
+bucket     = "dev-blog-tfstate"
+endpoints  = { s3 = "https://<account-id>.r2.cloudflarestorage.com" }
+access_key = "<R2_ACCESS_KEY_ID>"
+secret_key = "<R2_SECRET_ACCESS_KEY>"