Migrate CI/CD from Gitea Actions to Drone

Replace .gitea/workflows/docker.yml with .drone.yml using the Drone
Docker plugin with auto_tag enabled. On Git tag pushes (v0.2.0),
Drone automatically creates Docker image tags: full version (0.2.0),
minor version (0.2), and latest.

Updated docs/DEVELOPMENT.md to document Drone CI/CD setup instead
of Gitea Actions. Updated CHANGELOG.md to reflect the Drone migration.

Co-authored-by: Junie <junie@jetbrains.com>

.drone.yml

@@ -0,0 +1,21 @@
+kind: pipeline
+type: docker
+name: build-and-push
+
+trigger:
+  event:
+    - tag
+
+steps:
+  - name: build-and-push
+    image: plugins/docker
+    settings:
+      dockerfile: Dockerfile
+      context: .
+      registry: gitea.jambotron.com
+      repo: gitea.jambotron.com/liosha84/htop-web
+      auto_tag: true
+      username:
+        from: REGISTRY_USERNAME
+      password:
+        from: REGISTRY_PASSWORD