Weekly non-local-container task: localize the Tailscale operator stack on **both clusters**.
## What
- **`containers/tailscale-operator/`** (new) — builds `cmd/k8s-operator` v1.94.2 from the forge mirror, mirroring upstream's mkctr recipe (`/usr/local/bin/operator`, `ts_kube,ts_package_container` go tags, version stamps). `container.py` (dagger) for indri/arm64; `default.nix` for ringtail/amd64.
- **`containers/tailscale/container.py`** (new) — dagger/arm64 build of the proxy image (containerboot), mirroring the upstream Dockerfile (iptables-legacy symlinks, `/tailscale/run.sh` compat). Ringtail already consumes the existing nix build; this completes parity for indri.
- **Version pinned at v1.94.2** (same as currently deployed) — this PR is a pure supply-chain swap, no version change. v1.96.x is avoided deliberately (MagicDNS-in-containers regression).
- Docs-first: tailscale-operator card gains **Local Images** and **Rollout Safety** sections.
## Rollout plan (after image builds)
1. Manifest commit: per-overlay `images:` override for the operator + ProxyClass strategic-merge patch on indri (kustomize `images:` can't touch CR fields).
2. `argocd app set tailscale-operator --revision <branch> && argocd app sync` — indri first, verify, then ringtail.
3. **Shadow-device safety**: device identity lives in the tailscale state Secrets; an image swap re-uses existing node keys, so no `-1` clones. State Secrets are not touched. Post-sync verification: pod health, device names unchanged, `mise run services-check`.
## Follow-ups (not this PR)
- `dnsconfig` nameserver image (`tailscale/k8s-nameserver:stable`) still upstream.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Reviewed-on: #374
