fix: declare the nullplatform provider source in the install example

[jcastiarena]

What

Two things stop specs/install/aws/ from working the way the README documents it.

1. tofu init fails. There is no required_providers block, so OpenTofu infers the provider source as hashicorp/nullplatform:

Error: Failed to query available provider packages

Could not retrieve the list of available versions for provider
hashicorp/nullplatform: provider registry registry.opentofu.org does not have
a provider named registry.opentofu.org/hashicorp/nullplatform

Did you intend to use nullplatform/nullplatform? If so, you must specify that
source address in each module which requires that provider.

2. tofu apply does not authenticate. var.np_api_key only reaches the np CLI that the module dependencies shell out to; it never configures the Terraform provider, which falls back to the NULLPLATFORM_API_KEY environment variable. Following the README literally — fill in terraform.tfvars, then tofu init && tofu apply — fails to authenticate unless the operator also exports that variable, which the README does not mention.

So the documented install path does not work as written today.

Reproduce

git clone https://github.com/nullplatform/scopes-static-files
cd scopes-static-files/static-files/specs/install/aws
tofu init -backend=false

The change

Two files, no new inputs:

• versions.tf — declares the nullplatform/nullplatform provider source, plus a conservative required_version = ">= 1.6" floor.
• provider.tf — a provider "nullplatform" block wiring the existing var.np_api_key. The terraform.tfvars.example already prompts for it.

No provider version constraint, on purpose. Both tofu-modules dependencies already require ~> 0.0.86, so a root pin contributes no floor and only risks an unsatisfiable ceiling once the provider moves past 0.1.0. Happy to add one if you would rather the example pin explicitly.

Verification

After the change, both commands succeed on the example:

tofu init -backend=false   → OpenTofu has been successfully initialized!
tofu validate              → Success! The configuration is valid.

One caveat on the output: with provider 0.0.97 tofu validate reports a spurious np_apikey is deprecated warning for the new provider block even though only api_key is set. That is already fixed upstream and will clear on the provider's next release — api_key is the correct attribute.

[sebastiancorrea81]

lgtm