chore(ci): created forward-port.yml from ledoent/.github distributor

Author: dnplkndll

.github/workflows/forward-port.yml

@@ -0,0 +1,52 @@
+# MANAGED FILE — do not edit on this fork.
+#
+# This workflow is generated by the `forward-port-distributor` workflow
+# in `ledoent/.github`. Any edits here will be overwritten on the next
+# run. To change behaviour, edit
+#   ledoent/.github/.github/templates/forward-port.yml
+# and re-run the distributor (workflow_dispatch is fine).
+#
+# What it does: when a fork-internal PR is merged with a label of the
+# form `port:<branch>` (e.g. `port:19.0`), it cherry-picks the squash
+# commit onto `<branch>` and opens a follow-up PR. Conflicts are
+# reported in the PR body for manual resolution.
+#
+# Why it lives on every opted-in fork: the action triggers on
+# `pull_request: types: closed` on the host repo, so the workflow file
+# must exist there.
+
+name: forward-port
+
+on:
+  pull_request_target:
+    types: [closed]
+
+permissions:
+  contents: write
+  pull-requests: write
+
+jobs:
+  forward-port:
+    if: github.event.pull_request.merged == true
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Cherry-pick to labelled branches
+        uses: korthout/backport-action@v3
+        with:
+          # Label format: `port:19.0` → forward-port to branch 19.0.
+          # The action calls these "backport" but mechanically it's
+          # identical to forward-porting.
+          label_pattern: '^port:(?<target>.+)$'
+          pull_title: '[FP from #${pull_number}] ${pull_title}'
+          pull_description: |
+            Forward-port of #${pull_number} to `${target_branch}`.
+
+            **Conflicts to resolve** (if any) are listed below. Once the
+            branch is clean, mark this PR ready for review.
+
+            Original PR: #${pull_number}
+            Trigger: label `port:${target_branch}` on the merged PR.
+          merge_commits: skip