Add feature branch deployment pipeline

- Add deploy_feature job for ephemeral dev environments
- Use unique identifier (feat-{short_sha}) for K8s resource isolation
- Dynamic hostnames for ingress (orchard-{sha}.common.global.bsf.tools)
- Add cleanup_feature job with on_stop for automatic cleanup on merge
- Add values-dev.yaml with lighter resources for ephemeral deployments
- Refactor deploy_stage to use dynamic image tag from CI

CHANGELOG.md

@@ -6,6 +6,11 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Added
+- Added GitLab CI pipeline for feature branch deployments to dev namespace (#51)
+- Added `deploy_feature` job with dynamic hostnames and unique release names (#51)
+- Added `cleanup_feature` job with `on_stop` for automatic cleanup on merge (#51)
+- Added `values-dev.yaml` Helm values for lightweight ephemeral environments (#51)
 
 ## [0.4.0] - 2026-01-12
 ### Added