feat(pricing): add hcloud_pricing data source

[KamranBiglari]

Summary

Adds a new hcloud_pricing data source that exposes the prices for the resources offered by the Hetzner Cloud, mirroring the Pricing API.

Prices are returned for the Hetzner Cloud project the configured API token belongs to.

Exposed prices

• currency / vat_rate
• image (price per GB/month)
• floating_ips (per type, per location)
• primary_ips (per type, per location – hourly & monthly)
• server_backup (surcharge percentage)
• server_types (per type, per location – hourly, monthly, included traffic, per-TB traffic)
• load_balancer_types (per type, per location – hourly, monthly, included traffic, per-TB traffic)
• volume (price per GB/month)

Filters

The Pricing API has no server-side filtering, so the full response is fetched and filtered internally via optional inputs:

• location – restrict the per-location price lists to a single location
• server_type – restrict server_types to a single type (by name)
• load_balancer_type – restrict load_balancer_types to a single type (by name)

Implementation notes

• Built on the terraform-plugin-framework, following the existing data source style (internal/pricing, FromAPI/ToTerraform models, hcloudutil client wiring).
• Registered in hcloud/plugin_provider.go.
• Docs generated with tfplugindocs; example and acceptance test added.

Example

data "hcloud_pricing" "prices" {
  location    = "fsn1"
  server_type = "cx22"
}

output "cx22_monthly_gross" {
  value = data.hcloud_pricing.prices.server_types[0].prices[0].monthly.gross
}

Test plan

• go build ./..., go vet ./internal/pricing/..., gofmt clean
• go test ./internal/pricing/... passes
• TestAccPricingDataSource added (requires TF_ACC + a real token)