Migrate from Drone CI to Woodpecker CI

Replace .drone.yml with .woodpecker.yaml using official
woodpeckerci/plugin-kaniko image. Update base image to Alpine 3.22.2.

.woodpecker.yaml

@@ -0,0 +1,18 @@
+when:
+  - event: [push, pull_request, manual]
+
+steps:
+  - name: docker
+    image: woodpeckerci/plugin-kaniko
+    settings:
+      dockerfile: Dockerfile
+      registry: harbor.ntppool.org
+      repo: library/static-web
+      tags:
+        - ${CI_COMMIT_SHA:0:7}
+        - ${CI_COMMIT_BRANCH}
+      cache: true
+      username:
+        from_secret: harbor_library_username
+      password:
+        from_secret: harbor_library_password