[docs] Update changelog for v1.0.0-alpha.1: add cozystack-operator and backup system (#1867)

## What this PR does

Update changelog for v1.0.0-alpha.1 to include missing features:
- **Cozystack Operator**: New operator for Package and PackageSource
management (#1740, #1741, #1755, #1756, #1760, #1761)
- **Backup System**: Comprehensive backup functionality with Velero
integration (#1640, #1685, #1687, #1708, #1719, #1720, #1737, #1762)
- Add @androndo to contributors
- Update Full Changelog link to v0.38.0...v1.0.0-alpha.1

### Release note

```release-note
[docs] Update changelog for v1.0.0-alpha.1: add cozystack-operator and backup system
```

docs/changelogs/v1.0.0-alpha.1.md

@@ -1,6 +1,6 @@
 # Cozystack v1.0.0-alpha.1 — "Package-Based Architecture"
 
-This alpha release introduces a fundamental architectural shift from HelmRelease bundles to Package-based deployment managed by the cozystack-operator. It includes significant API changes that rename the core CRD, Flux sharding for improved tenant workload distribution, enhanced monitoring capabilities, and various improvements to virtual machines, tenants, and the build workflow.
+This alpha release introduces a fundamental architectural shift from HelmRelease bundles to Package-based deployment managed by the new cozystack-operator. It includes a comprehensive backup system with Velero integration, significant API changes that rename the core CRD, Flux sharding for improved tenant workload distribution, enhanced monitoring capabilities, and various improvements to virtual machines, tenants, and the build workflow.
 
 > **⚠️ Alpha Release Warning**: This is a pre-release version intended for testing and early adoption. Breaking changes may occur before the stable v1.0.0 release.
 
@@ -28,6 +28,29 @@ The platform now uses Package resources managed by cozystack-operator instead of
 
 ## Major Features and Improvements
 
+### Cozystack Operator
+
+A new operator has been introduced to manage Package and PackageSource resources, providing declarative package management for the platform:
+
+* **[cozystack-operator] Introduce API objects: packages and packagesources**: Added new CRDs for declarative package management, defining the API for Package and PackageSource resources ([**@kvaps**](https://github.com/kvaps) in #1740).
+* **[cozystack-operator] Introduce Cozystack-operator core logic**: Implemented core reconciliation logic for the operator, handling Package and PackageSource lifecycle management ([**@kvaps**](https://github.com/kvaps) in #1741).
+* **[cozystack-operator] Add Package and PackageSource reconcilers**: Added controllers for Package and PackageSource resources with full reconciliation support ([**@kvaps**](https://github.com/kvaps) in #1755).
+* **[cozystack-operator] Add deployment files**: Added Kubernetes deployment manifests for running cozystack-operator in the cluster ([**@kvaps**](https://github.com/kvaps) in #1761).
+* **[platform] Add PackageSources for cozystack-operator**: Added PackageSource definitions for cozystack-operator integration ([**@kvaps**](https://github.com/kvaps) in #1760).
+* **[cozypkg] Add tool for managing Package and PackageSources**: Added CLI tool for managing Package and PackageSource resources ([**@kvaps**](https://github.com/kvaps) in #1756).
+
+### Backup System
+
+Comprehensive backup functionality has been added with Velero integration for managing application backups:
+
+* **[backups] Implement core backup Plan controller**: Core controller for managing backup schedules and plans, providing the foundation for backup orchestration ([**@lllamnyp**](https://github.com/lllamnyp) in #1640).
+* **[backups] Build and deploy backup controller**: Deployment infrastructure for the backup controller, including container image builds and Kubernetes manifests ([**@lllamnyp**](https://github.com/lllamnyp) in #1685).
+* **[backups] Scaffold a backup strategy API group**: Added API group for backup strategies, enabling pluggable backup implementations ([**@lllamnyp**](https://github.com/lllamnyp) in #1687).
+* **[backups] Add indices to core backup resources**: Added indices to backup resources for improved query performance ([**@lllamnyp**](https://github.com/lllamnyp) in #1719).
+* **[backups] Stub the Job backup strategy controller**: Added stub implementation for Job-based backup strategy ([**@lllamnyp**](https://github.com/lllamnyp) in #1720).
+* **[backups] Implement Velero strategy controller**: Integration with Velero for backup operations, enabling enterprise-grade backup capabilities ([**@androndo**](https://github.com/androndo) in #1762).
+* **[backups,dashboard] User-facing UI**: Dashboard interface for managing backups and backup jobs, providing visibility into backup status and history ([**@lllamnyp**](https://github.com/lllamnyp) in #1737).
+
 ### Platform Architecture
 
 * **[platform] Migrate from HelmRelease bundles to Package-based deployment**: Replaced HelmRelease bundle system with Package resources managed by cozystack-operator. Includes restructured values.yaml with full configuration support and migration tooling ([**@kvaps**](https://github.com/kvaps) in #1816).
@@ -63,6 +86,7 @@ The platform now uses Package resources managed by cozystack-operator instead of
 
 * **fix(talos): skip rebuilding assets if files already exist**: Improved Talos package build process to avoid redundant asset rebuilds when files are already present, reducing build time ([**@kvaps**](https://github.com/kvaps)).
 * **[kubevirt-operator] Fix typo in VMNotRunningFor10Minutes alert**: Fixed typo in VM alert name, ensuring proper alert triggering and monitoring for virtual machines that are not running for extended periods ([**@lexfrei**](https://github.com/lexfrei) in #1770, #1775).
+* **[backups] Fix malformed glob and split in template**: Fixed malformed glob pattern and split operation in backup template processing ([**@lllamnyp**](https://github.com/lllamnyp) in #1708).
 
 ## Documentation
 
@@ -74,7 +98,7 @@ The platform now uses Package resources managed by cozystack-operator instead of
 
 ## Migration Guide
 
-### From v0.39.x / v0.40.x to v1.0.0-alpha.1
+### From v0.38.x / v0.39.x to v1.0.0-alpha.1
 
 1. **Backup your cluster** before upgrading
 2. Run the migration script: `hack/migrate-to-version-1.0.sh`
@@ -94,6 +118,7 @@ The platform now uses Package resources managed by cozystack-operator instead of
 
 We'd like to thank all contributors who made this release possible:
 
+* [**@androndo**](https://github.com/androndo)
 * [**@IvanHunters**](https://github.com/IvanHunters)
 * [**@kvaps**](https://github.com/kvaps)
 * [**@lexfrei**](https://github.com/lexfrei)
@@ -102,7 +127,7 @@ We'd like to thank all contributors who made this release possible:
 
 ---
 
-**Full Changelog**: [v0.39.0...v1.0.0-alpha.1](https://github.com/cozystack/cozystack/compare/v0.39.0...v1.0.0-alpha.1)
+**Full Changelog**: [v0.38.0...v1.0.0-alpha.1](https://github.com/cozystack/cozystack/compare/v0.38.0...v1.0.0-alpha.1)
 
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 https://github.com/cozystack/cozystack/releases/tag/v1.0.0-alpha.1