chore(ci): replace mirror.yml with reusable wrapper (#67)

Pins to hyperpolymath/standards#187 merge SHA e6b2884722350515934d443daf23442f2195796f. Replaces the
canonical mirror.yml (~145 lines, drift-prone) with a thin ~13-line
wrapper. Forge selection still externalised to vars.<FORGE>_MIRROR_ENABLED.

Part of estate-wide convergence campaign 2026-05-26
(standards#199 / #187).

Author: hyperpolymath

.github/workflows/mirror.yml

@@ -1,5 +1,4 @@
 # SPDX-License-Identifier: MPL-2.0
-# SPDX-FileCopyrightText: 2026 Jonathan D.A. Jewell
 name: Mirror to Git Forges
 
 on:
@@ -11,56 +10,6 @@ permissions:
   contents: read
 
 jobs:
-  mirror-gitlab:
-    runs-on: ubuntu-latest
-    if: vars.GITLAB_MIRROR_ENABLED == 'true'
-    steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-        with:
-          fetch-depth: 0
-
-      - uses: webfactory/ssh-agent@a6f90b1f127823b31d4d4a8d96047790581349bd # v0.9.1
-        with:
-          ssh-private-key: ${{ secrets.GITLAB_SSH_KEY }}
-
-      - name: Mirror to GitLab
-        run: |
-          ssh-keyscan -t ed25519 gitlab.com >> ~/.ssh/known_hosts
-          git remote add gitlab git@gitlab.com:${{ vars.GITLAB_ORG || vars.MIRROR_ORG || github.repository_owner }}/${{ github.event.repository.name }}.git || true
-          git push --force gitlab main
-
-  mirror-bitbucket:
-    runs-on: ubuntu-latest
-    if: vars.BITBUCKET_MIRROR_ENABLED == 'true'
-    steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-        with:
-          fetch-depth: 0
-
-      - uses: webfactory/ssh-agent@a6f90b1f127823b31d4d4a8d96047790581349bd # v0.9.1
-        with:
-          ssh-private-key: ${{ secrets.BITBUCKET_SSH_KEY }}
-
-      - name: Mirror to Bitbucket
-        run: |
-          ssh-keyscan -t ed25519 bitbucket.org >> ~/.ssh/known_hosts
-          git remote add bitbucket git@bitbucket.org:${{ vars.BITBUCKET_ORG || vars.MIRROR_ORG || github.repository_owner }}/${{ github.event.repository.name }}.git || true
-          git push --force bitbucket main
-
-  mirror-codeberg:
-    runs-on: ubuntu-latest
-    if: vars.CODEBERG_MIRROR_ENABLED == 'true'
-    steps:
-      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd # v6.0.2
-        with:
-          fetch-depth: 0
-
-      - uses: webfactory/ssh-agent@a6f90b1f127823b31d4d4a8d96047790581349bd # v0.9.1
-        with:
-          ssh-private-key: ${{ secrets.CODEBERG_SSH_KEY }}
-
-      - name: Mirror to Codeberg
-        run: |
-          ssh-keyscan -t ed25519 codeberg.org >> ~/.ssh/known_hosts
-          git remote add codeberg git@codeberg.org:${{ vars.CODEBERG_ORG || vars.MIRROR_ORG || github.repository_owner }}/${{ github.event.repository.name }}.git || true
-          git push --force codeberg main
+  mirror:
+    uses: hyperpolymath/standards/.github/workflows/mirror-reusable.yml@e6b2884722350515934d443daf23442f2195796f
+    secrets: inherit