Regenerate docs, update CHANGELOG for v1.0.0, clean up registry manifest

- Regenerated docs/ via tfplugindocs: 51 files covering all 20 resources
  and 30 data sources with auto-extracted schemas and examples
- Removed stale docs for old resources (build.md, ssh.md)
- CHANGELOG.md: added v1.0.0 entry with full feature list, breaking
  changes, and security notes
- terraform-registry-manifest.json: confirmed protocol_versions ["6.0"]
  is correct for Terraform Plugin Framework

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

docs/data-sources/self_service_usage.md

@@ -0,0 +1,25 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "virtfusion_self_service_usage Data Source - virtfusion"
+subcategory: ""
+description: |-
+  Fetches VirtFusion self-service usage data for a user and group.
+---
+
+# virtfusion_self_service_usage (Data Source)
+
+Fetches VirtFusion self-service usage data for a user and group.
+
+
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Required
+
+- `group_id` (Number) The group ID to fetch usage data for.
+- `user_id` (Number) The user ID to fetch usage data for.
+
+### Read-Only
+
+- `usage_json` (String) The raw JSON response containing usage data.