Add CI, repo CLAUDE.md, and finish Stage 0

- .gitea/workflows/ci.yaml: fmt/lint/test, same no-actions/checkout-and-manual-clone
  shape as terdut-server's ci.yaml, and the same reasoning for why (Node/ES2022
  incompatibility on the runner image). No chart/security jobs yet -- nothing for
  either to check until Stage 6 / real controller code exists.
- CLAUDE.md: Checks + Release sections, matching the sibling repos' convention from
  the workspace-level CLAUDE.md ("each repo has its own CLAUDE.md... read it before
  working in that repo"). Release is explicitly marked not-wired-yet rather than
  copying terdut-server's, since there's no chart to release against until Stage 6.
- ROADMAP.md: moved the .release.conf bullet out of Stage 0 (it names a HELM_CHART
  this repo doesn't have yet) -- it was already duplicated into Stage 6, which is
  where it actually belongs.

Stage 0 done: `make fmt lint test` verified green locally. Real open question the CI
workflow's comments flag rather than assume past: whether storage.googleapis.com
(envtest's binary source) is reachable from this Gitea runner's container network the
way proxy.golang.org is -- terdut-server's own ci.yaml notes get.helm.sh/github.com are
not. Only running the workflow for real will confirm; the comment names the fallback
(move the job out of `container:`, like terdut-server's chart job) if it isn't.

ROADMAP.md

@@ -24,18 +24,25 @@ land in Stage 5, not before.
 
 ## Stage 0 — Scaffolding & CI
 
-- `go.mod` (`git.ryuvia.com/niklas/terdut-operator`) + Kubebuilder scaffold
-  (`cmd/main.go`, `config/`, `Makefile`, `PROJECT`), matching terdut-server's
-  Go toolchain and house style (§3).
-- `.release.conf` + a release-vars Makefile target, same shape as
-  terdut-server's — this repo ships a Helm chart (§1, §10), so it follows
-  the wrapper-chart release path, not terdut-tui's binary-only one.
-- Gitea Actions CI calling `fmt lint test helm-lint`, mirroring
-  terdut-server's `ci.yaml`/`release.yaml` convention (its `CLAUDE.md`: "a
-  green gate here and a green pipeline are the same code, not two
-  descriptions of it").
-- Install `setup-envtest`, wire it into `make test` so the `envtest` suite
-  (§11) runs without needing the full `kubebuilder` CLI at test time.
+- `go.mod` (`git.ryuvia.com/niklas/terdut-operator`) + Kubebuilder v4
+  scaffold (`cmd/main.go`, `config/`, `Makefile`, `PROJECT`), matching
+  terdut-server's Go toolchain and house style (§3). Kubebuilder's own
+  scaffolded `Makefile` already wires `manifests`/`generate`
+  (`controller-gen`) and `setup-envtest` into `test`, and `golangci-lint`
+  into `lint`, all fetched on demand into `bin/` — no separate install
+  step needed beyond what `make test`/`make lint` already do.
+- `.release.conf` deliberately **not** added yet: it names a `HELM_CHART`
+  this repo doesn't have until Stage 6. Adding it now would either be a
+  stub that lies about what's releasable or dead config nobody can run —
+  it lands in Stage 6, alongside the chart it describes.
+- Gitea Actions CI calling `fmt lint test`, mirroring terdut-server's
+  `ci.yaml` convention (its `CLAUDE.md`: "a green gate here and a green
+  pipeline are the same code, not two descriptions of it") minus the
+  `chart`/`security` jobs, which need a chart (Stage 6) and real controller
+  code (Stage 1+) respectively to have anything to check.
+- Drop kubebuilder's default `.github/workflows/*` scaffold — this org
+  runs on Gitea, not GitHub; `.gitea/workflows/ci.yaml` is the only CI this
+  repo has.
 - Housekeeping: drop the stray `.DESIGN.md.swp` (leftover vim swapfile,
   shouldn't be committed); correct `DESIGN.md` §6/§13's "v1-blocking, not
   v1-shippable" language — the service-account feature it was blocking on