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/resources/user.md

@@ -0,0 +1,35 @@
+---
+# generated by https://github.com/hashicorp/terraform-plugin-docs
+page_title: "virtfusion_user Resource - virtfusion"
+subcategory: ""
+description: |-
+  Manages a VirtFusion user.
+---
+
+# virtfusion_user (Resource)
+
+Manages a VirtFusion user.
+
+## Example Usage
+
+```terraform
+resource "virtfusion_user" "customer1" {
+  name            = "John Doe"
+  email           = "john@example.com"
+  ext_relation_id = "cust-12345"
+}
+```
+
+<!-- schema generated by tfplugindocs -->
+## Schema
+
+### Required
+
+- `email` (String) The email address of the user.
+- `ext_relation_id` (String) The external relation ID used to look up the user. Changing this forces a new resource to be created.
+- `name` (String) The name of the user.
+
+### Read-Only
+
+- `enabled` (Boolean) Whether the user is enabled.
+- `id` (Number) The numeric ID of the user.