Move all e2e test logic from bash steps in ci.yaml into Go test files
under test/e2e/. CI now sets up infrastructure (KinD, Knative, CRDs,
controllers, Gitea) then runs `go test -tags=e2e ./test/e2e/`.
Benefits:
- Tests run concurrently via t.Parallel()
- No more bash-in-YAML maintenance burden
- Each test creates its own isolated resources with cleanup
- Proper Go test output with -v
- Build-tagged so `go test ./...` skips them
Tests:
- TestPushTransaction: push main to a new branch, verify on git server
- TestPushTransactionMultipleRefSpecs: push to two branches at once
- TestRepoSync: create two repos, set up GitRepoSync, verify controller
https://claude.ai/code/session_01QfFzqKQUsxxBsiZUhuJ3pG
