Harden read-only provider with tests, docs, and CI

docs/index.md

@@ -0,0 +1,32 @@
+---
+page_title: "dynu Provider"
+description: |-
+  Terraform provider for Dynu DNS read-only data sources.
+---
+
+# dynu Provider
+
+The `dynu` provider lets Terraform read Dynu DNS domain and record data.
+
+## Example Usage
+
+```terraform
+terraform {
+  required_providers {
+    dynu = {
+      source = "dynu/dynu"
+    }
+  }
+}
+
+provider "dynu" {
+  api_key = var.dynu_api_key
+}
+```
+
+## Schema
+
+### Optional
+
+- `api_key` (String, Sensitive) Dynu API key. If omitted, `DYNU_API_KEY` is used.
+- `base_url` (String) Override API base URL. Primarily intended for automated tests.