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/user.md

@@ -0,0 +1,29 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "virtfusion_user Data Source - virtfusion"
+subcategory: ""
+description: |-
+  Fetches a VirtFusion user by external relation ID.
+---
+
+# virtfusion_user (Data Source)
+
+Fetches a VirtFusion user by external relation ID.
+
+
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Required
+
+- `ext_relation_id` (String) The external relation ID of the user.
+
+### Read-Only
+
+- `created_at` (String) The creation timestamp.
+- `email` (String) The user email address.
+- `enabled` (Boolean) Whether the user is enabled.
+- `id` (Number) The numeric ID of the user.
+- `name` (String) The user name.
+- `updated_at` (String) The last update timestamp.