ci: add dispatch-only kaniko-act build, targeting the org registry

Bootstrap step for moving container images off the personal namespace.
Builds using the existing mikkeli/kaniko-act; the org copy is what this
run produces.

.gitea/workflows/build-kaniko-act.yml

@@ -0,0 +1,60 @@
+# Rebuilds the kaniko-act builder image.
+#
+# Dispatch-only on purpose. This is the image build-image.yml runs inside, so
+# an automatic trigger could push a broken builder and take the whole build
+# path down with it. Bump deliberately, verify, then repoint build-image.yml.
+#
+# Self-hosting: builds the new kaniko-act using the *previous* kaniko-act, per
+# the bootstrap note in ci/Dockerfile.kaniko-act.
+on:
+  workflow_dispatch:
+    inputs:
+      VERSION:
+        description: "Tag to publish, e.g. v1.23.2-r2"
+        required: true
+        type: string
+        default: v1.23.2-r2
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    container:
+      # BOOTSTRAP: still the pre-migration image under `mikkeli`, because the
+      # org copy is what this run creates. Flip to the org path once it exists.
+      image: pi5-16.local:3005/mikkeli/kaniko-act:v1.23.2-r2
+
+    steps:
+      - name: Fetch source, build, push
+        # kaniko image has no bash — busybox sh only
+        shell: sh
+        env:
+          # package r/w PAT (org-level secret) — registry push only
+          PKG_TOKEN: ${{ secrets.PKGRW_PAT }}
+          # per-run auto-token, read access to this repo only — source fetch
+          JOB_TOKEN: ${{ github.token }}
+          URL_TO_GITEA: ${{ vars.URL_TO_GITEA }}
+          VERSION: ${{ inputs.VERSION }}
+        run: |
+          set -eu
+          HOST="${URL_TO_GITEA#http://}"
+          IMAGE="${HOST}/novoyuuparosk-wiki/kaniko-act"
+
+          wget -qO /tmp/src.tar.gz \
+            "http://mikkeli:${JOB_TOKEN}@${HOST}/api/v1/repos/novoyuuparosk-wiki/novoyuuparosk-auto-wiki/archive/${GITHUB_SHA}.tar.gz"
+          mkdir -p /tmp/src
+          tar -xzf /tmp/src.tar.gz -C /tmp/src --strip-components=1
+
+          # Registry auth for the push
+          AUTH=$(printf '%s' "mikkeli:${PKG_TOKEN}" | base64 | tr -d '\n')
+          printf '{"auths":{"%s":{"auth":"%s"}}}' "${HOST}" "${AUTH}" \
+            > /kaniko/.docker/config.json
+
+          # --insecure: push target is the plain-HTTP Gitea registry.
+          # Base image pull (gcr.io) stays HTTPS — no --insecure-pull.
+          /kaniko/executor \
+            --context dir:///tmp/src \
+            --dockerfile /tmp/src/ci/Dockerfile.kaniko-act \
+            --destination "${IMAGE}:${VERSION}" \
+            --insecure
+
+          echo "Pushed ${IMAGE}:${VERSION}"