Add k3s, 1Password Connect, and systemd nix-container-builder to ringtail (#209)

## Summary

  Extends ringtail from a desktop/gaming NixOS box into an infrastructure node with a k3s cluster, secrets management, and a Forgejo Actions
  runner for building containers with Nix.

  ### K3s cluster
  - Single-node k3s with Traefik/ServiceLB/metrics-server disabled (minimal footprint)
  - TLS SAN set to `ringtail.tail8d86e.ts.net` so ArgoCD on indri can manage it via Tailscale
  - Containerd registry mirrors pull through Zot on indri (`k3s-registries.yaml`)
  - Tailscale interface added to `trustedInterfaces` for cross-node ArgoCD access
  - `kubectl` added to system packages

  ### 1Password Connect + External Secrets Operator
  - Four new ArgoCD apps targeting `k3s-ringtail`: `1password-connect-ringtail`, `external-secrets-crds-ringtail`, `external-secrets-ringtail`,
  `external-secrets-config-ringtail`
  - Reuses the same Helm charts/values as indri, just pointed at ringtail's k3s API server
  - Bootstrap secrets (`op-credentials`, `onepassword-token`) provisioned by Ansible pre_tasks via `op read`, then applied to the `1password`
  namespace in post_tasks

  ### Systemd Forgejo Actions runner
  - Native `services.gitea-actions-runner` with `forgejo-runner` package — no DinD, no k8s pod, runs directly on the NixOS host
  - Label `nix-container-builder:host` — jobs execute on the host with `nix`, `skopeo`, `nodejs`, etc. in PATH
  - Registration token fetched from 1Password (`Forgejo Secrets/runner_reg`) by Ansible and written to `/etc/forgejo-runner/token.env`
  - Runner's dynamic user (`gitea-runner`) added to `nix.settings.trusted-users` for nix daemon access

  ### Nix container build workflow
  - New `.forgejo/workflows/build-container-nix.yaml` triggers on `*-nix-v[0-9]*` tags (e.g. `nettest-nix-v1.0.0`)
  - Builds with `nix build -f containers/<name>/default.nix`, pushes to Zot via `skopeo copy`
  - Existing Dockerfile workflow guarded with `if: !contains(github.ref_name, '-nix-v')` to avoid double-triggering

  ### Mise task updates
  - `container-tag-and-release` auto-detects `default.nix` vs `Dockerfile` and uses the appropriate tag format (`-nix-v` vs `-v`)
  - `container-list` shows build type indicator (`[nix]` / `[dockerfile]`)

  ## Post-merge

  1. `mise run provision-ringtail` — deploys k3s token, runner token, NixOS rebuild
  2. Register k3s cluster in ArgoCD (first time only):
     ```fish
     ssh ringtail 'sudo cat /etc/rancher/k3s/k3s.yaml' | \
       sed 's|127.0.0.1|ringtail.tail8d86e.ts.net|' > /tmp/k3s-ringtail.yaml
     set -x KUBECONFIG /tmp/k3s-ringtail.yaml
     argocd cluster add default --name k3s-ringtail
  3. Sync ArgoCD apps in order: 1password-connect-ringtail -> external-secrets-crds-ringtail -> external-secrets-ringtail ->
  external-secrets-config-ringtail
  4. Verify runner: ssh ringtail 'systemctl status gitea-runner-nix-container-builder'
  5. Check Forgejo admin panel for ringtail-nix-builder runner online
  6. Test: create containers/<name>/default.nix, tag with <name>-nix-v0.1.0

Reviewed-on: https://forge.ops.eblu.me/eblume/blumeops/pulls/209

ansible/playbooks/ringtail.yml

@@ -3,6 +3,57 @@
   hosts: ringtail
   become: true
 
+  pre_tasks:
+    - name: Fetch 1Password Connect credentials from 1Password
+      ansible.builtin.command:
+        cmd: op read "op://vg6xf6vvfmoh5hqjjhlhbeoaie/1Password Connect/credentials-file"
+      register: _op_credentials
+      changed_when: false
+      delegate_to: localhost
+      become: false
+
+    - name: Fetch 1Password Connect token from 1Password
+      ansible.builtin.command:
+        cmd: op read "op://vg6xf6vvfmoh5hqjjhlhbeoaie/1Password Connect/token"
+      register: _op_token
+      changed_when: false
+      delegate_to: localhost
+      become: false
+
+    - name: Fetch Forgejo runner registration token from 1Password
+      ansible.builtin.command:
+        cmd: op read "op://vg6xf6vvfmoh5hqjjhlhbeoaie/Forgejo Secrets/runner_reg"
+      register: _runner_reg
+      changed_when: false
+      delegate_to: localhost
+      become: false
+
+    - name: Ensure /etc/forgejo-runner directory exists
+      ansible.builtin.file:
+        path: /etc/forgejo-runner
+        state: directory
+        mode: "0700"
+
+    - name: Write Forgejo runner token file
+      ansible.builtin.copy:
+        content: "TOKEN={{ _runner_reg.stdout }}"
+        dest: /etc/forgejo-runner/token.env
+        mode: "0600"
+      no_log: true
+
+    - name: Ensure /etc/k3s directory exists
+      ansible.builtin.file:
+        path: /etc/k3s
+        state: directory
+        mode: "0700"
+
+    - name: Generate k3s token if not present
+      ansible.builtin.copy:
+        content: "{{ lookup('ansible.builtin.password', '/dev/null', chars=['hexdigits'], length=32) }}"
+        dest: /etc/k3s/token
+        mode: "0600"
+        force: false
+
   tasks:
     - name: Ensure blumeops repo is present
       ansible.builtin.git:
@@ -24,3 +75,42 @@
       register: _ts_status
       changed_when: false
       failed_when: "'Running' not in _ts_status.stdout"
+
+  post_tasks:
+    - name: Wait for k3s to be ready
+      ansible.builtin.command: k3s kubectl get nodes
+      register: _k3s_ready
+      changed_when: false
+      retries: 30
+      delay: 5
+      until: _k3s_ready.rc == 0
+
+    - name: Create 1password namespace
+      ansible.builtin.command: k3s kubectl create namespace 1password
+      register: _ns
+      changed_when: _ns.rc == 0
+      failed_when: _ns.rc != 0 and 'AlreadyExists' not in _ns.stderr
+
+    - name: Create or update op-credentials secret
+      ansible.builtin.shell:
+        cmd: |
+          set -o pipefail
+          k3s kubectl create secret generic op-credentials \
+            --namespace=1password \
+            --from-literal=1password-credentials.json='{{ _op_credentials.stdout }}' \
+            --dry-run=client -o yaml | k3s kubectl apply -f -
+        executable: /run/current-system/sw/bin/bash
+      changed_when: true
+      no_log: true
+
+    - name: Create or update onepassword-token secret
+      ansible.builtin.shell:
+        cmd: |
+          set -o pipefail
+          k3s kubectl create secret generic onepassword-token \
+            --namespace=1password \
+            --from-literal=token={{ _op_token.stdout }} \
+            --dry-run=client -o yaml | k3s kubectl apply -f -
+        executable: /run/current-system/sw/bin/bash
+      changed_when: true
+      no_log: true