ci: add workflow_dispatch trigger to post-merge workflow

.gitea/workflows/post-merge.yml

@@ -21,6 +21,9 @@ name: Post-merge
 on:
   push:
     branches: [master]
+  # Implements: REQ-1 — manual recovery when a [skip ci] squash title
+  # suppresses the push-triggered post-merge run.
+  workflow_dispatch:
 
 concurrency:
   group: post-merge-${{ github.ref }}

docs/specs/DEVX-180.md

@@ -0,0 +1,35 @@
+# DEVX-180: Add workflow_dispatch trigger to post-merge workflow
+
+## Problem
+
+When auto-merge produces a `[skip ci]` squash title (DEVX-179), the
+post-merge push run is suppressed — release, publish, wiki sync, Vikunja
+close, and badges are all skipped with no manual recovery path, because
+`post-merge.yml` only triggers on `push`.
+
+## Approach
+
+REQ-1: Add `workflow_dispatch:` to the `on:` block of
+`.gitea/workflows/post-merge.yml` so a missed or skipped post-merge run
+can be dispatched manually on master.
+
+## Test Plan
+
+- `make workflow-check` (actionlint + act_runner dryrun) validates the
+  trigger syntax.
+- Post-merge: dispatch the workflow manually once and confirm it runs
+  on master.
+
+## Deploy Plan
+
+Merge → post-merge push run fires normally → then dispatch
+`post-merge.yml` on master to recover the suppressed DEVX-178 release.
+
+## Rollback Plan
+
+Revert the one-line trigger addition.
+
+## Acceptance Criteria
+
+- [x] REQ-1: `workflow_dispatch` present in `post-merge.yml` `on:` block;
+  actionlint and act_runner dryrun pass.