Scaffold proxy-operator with kubebuilder v4.15.0 (go/v4)

Bootstraps the empty repo into a kubebuilder go/v4 project: group
crawl.example.com, version v1alpha1, kind Proxy (namespaced). Keeps the
existing module path and preserves the repo's Go/testing/changelog
conventions from CLAUDE.md untouched.

Drops the scaffolded GitHub Actions workflows since the remote is Gitea,
not GitHub. Everything else is default kubebuilder output, unmodified,
so later diffs stay reviewable against a known baseline.

Full implementation plan: docs/plans/2026-08-07-1747-proxy-operator.md

Co-Authored-By: Claude <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,11 @@
+# More info: https://docs.docker.com/engine/reference/builder/#dockerignore-file
+# Ignore everything by default and re-include only needed files
+**
+
+# Re-include Go source files (but not *_test.go)
+!**/*.go
+**/*_test.go
+
+# Re-include Go module files
+!go.mod
+!go.sum