Overhaul VirtFusion provider: 20 resources, 30 data sources, multipage pagination

Complete rewrite of the VirtFusion Terraform provider with full API coverage:

- 20 managed resources (server, build, SSH key, user, firewall, IP blocks, etc.)
- 30 data sources (hypervisors, packages, servers, IP blocks, self-service, etc.)
- New HTTP client with proper error handling, query parameter support, and
  automatic multipage pagination via GetAllPages (fetches all pages from
  Laravel-style paginated endpoints and merges into a single response)
- Fixed type mismatches against live API: ServerData.Suspended (int→bool),
  IPBlockData.Type (string→int), PackageData json tags (primaryStorage, etc.),
  ServerData nested CPU/Settings/Resources structure, HypervisorGroupResources
  array response
- Configurable results-per-page (default 300) on all list data sources
- Migrated CI from GitHub Actions to Gitea Actions
- Updated goreleaser config, go.mod dependencies, and examples

Verified against live VirtFusion instance at cp.vps.ezscale.tech:
all data sources return correct data with full pagination support.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

internal/client/errors.go

@@ -0,0 +1,34 @@
+// Copyright (c) EZSCALE.
+// SPDX-License-Identifier: MPL-2.0
+
+package client
+
+import "fmt"
+
+// APIError represents an error returned by the VirtFusion API.
+type APIError struct {
+	StatusCode int
+	Status     string
+	Body       string
+	Errors     map[string][]string
+}
+
+func (e *APIError) Error() string {
+	if len(e.Errors) > 0 {
+		return fmt.Sprintf("VirtFusion API error %d (%s): %v", e.StatusCode, e.Status, e.Errors)
+	}
+	if e.Body != "" {
+		return fmt.Sprintf("VirtFusion API error %d (%s): %s", e.StatusCode, e.Status, e.Body)
+	}
+	return fmt.Sprintf("VirtFusion API error %d (%s)", e.StatusCode, e.Status)
+}
+
+// IsNotFound returns true if the error is a 404 Not Found response.
+func (e *APIError) IsNotFound() bool {
+	return e.StatusCode == 404
+}
+
+// IsValidationError returns true if the error is a 422 Unprocessable Entity response.
+func (e *APIError) IsValidationError() bool {
+	return e.StatusCode == 422
+}