ci(pythonpublish): add workflow_dispatch trigger for republishing tags (#1981)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: bearomorphism

.github/workflows/pythonpublish.yml

@@ -5,6 +5,15 @@ on:
   push:
     tags:
       - "v*"
+  # Manual trigger for republishing a specific tag if the original push-on-tag
+  # run failed and is now too old to be re-run via the GitHub UI (#1790).
+  # ``ref`` should be a tag name like ``v4.11.1``.
+  workflow_dispatch:
+    inputs:
+      ref:
+        description: "Tag to republish (e.g., v4.11.1)"
+        required: true
+        type: string
 
 jobs:
   deploy:
@@ -14,10 +23,19 @@ jobs:
       id-token: write
       contents: read
     steps:
+      - name: Validate dispatch ref is a tag
+        if: github.event_name == 'workflow_dispatch'
+        env:
+          TAG: ${{ github.event.inputs.ref }}
+        run: |
+          if ! git ls-remote --tags "https://github.com/${GITHUB_REPOSITORY}" "refs/tags/${TAG}" | grep -q .; then
+            echo "::error::Dispatch ref '${TAG}' is not an existing tag"
+            exit 1
+          fi
       - uses: actions/checkout@v6
         with:
           fetch-depth: 0
-          ref: ${{ github.ref_name }}
+          ref: ${{ github.event_name == 'workflow_dispatch' && format('refs/tags/{0}', github.event.inputs.ref) || github.ref }}
       - name: Set up Python
         uses: astral-sh/setup-uv@v7
       - name: Build