cloudflare-pages-preview: add comment-mode=repost, extract scripts

New comment-mode input:
- 'sticky' (default, backwards-compat): update the existing marker comment
  in place — same behavior as before
- 'repost': minimize all prior marker comments as OUTDATED (GitHub's native
  hide-comment UI via GraphQL minimizeComment mutation) and post a fresh
  comment at the bottom of the conversation

Useful for /stageblog where each staging should produce a visible new
comment while keeping history collapsible rather than lost.

Both deploy and cleanup accept the input and must match. cleanup in repost
mode minimizes all prior comments and posts a final cleanup note.

Also:
- Extract both comment scripts to sibling comment.js files (same pattern as
  slash-commands/main.js) — the inline YAML scripts were getting long
- Paginate listComments (was only fetching the first 30)

cloudflare-pages-preview/cleanup/action.yml

@@ -22,6 +22,13 @@ inputs:
     description: HTML comment marker used to locate the sticky PR comment
     required: false
     default: '<!-- cf-pages-preview -->'
+  comment-mode:
+    description: >-
+      Must match the deploy action's comment-mode. 'sticky' (default) updates
+      the single marker comment in place. 'repost' minimizes all marker
+      comments as OUTDATED and posts a final cleanup comment.
+    required: false
+    default: sticky
   github-token:
     description: GitHub token for updating the PR comment
     required: false
@@ -72,28 +79,10 @@ runs:
       uses: actions/github-script@v8
       env:
         COMMENT_MARKER: ${{ inputs.comment-marker }}
+        COMMENT_MODE: ${{ inputs.comment-mode }}
         PR_NUMBER: ${{ inputs.pr-number }}
       with:
         github-token: ${{ inputs.github-token }}
         script: |
-          const { owner, repo } = context.repo;
-          const prNumber = Number(process.env.PR_NUMBER);
-          if (!prNumber) {
-            core.info('No PR number available — skipping comment update.');
-            return;
-          }
-          const marker = process.env.COMMENT_MARKER;
-
-          const { data: comments } = await github.rest.issues.listComments({
-            owner, repo, issue_number: prNumber
-          });
-          const existing = comments.find(c =>
-            c.user.type === 'Bot' && c.body.includes(marker)
-          );
-
-          if (existing) {
-            await github.rest.issues.updateComment({
-              owner, repo, comment_id: existing.id,
-              body: `${marker}\n## Preview\n\n_Preview deployments for this PR have been cleaned up._`
-            });
-          }
+          const main = require(process.env.GITHUB_ACTION_PATH + '/comment.js');
+          await main({ github, context, core });

cloudflare-pages-preview/cleanup/comment.js

@@ -0,0 +1,51 @@
+// Updates the PR preview comment after deployments are deleted. Called by
+// actions/github-script via `require(GITHUB_ACTION_PATH + '/comment.js')`.
+
+module.exports = async ({ github, context, core }) => {
+  const { owner, repo } = context.repo;
+  const prNumber = Number(process.env.PR_NUMBER);
+  if (!prNumber) {
+    core.info('No PR number available — skipping comment update.');
+    return;
+  }
+  const marker = process.env.COMMENT_MARKER;
+  const mode = process.env.COMMENT_MODE;
+
+  const comments = await github.paginate(github.rest.issues.listComments, {
+    owner, repo, issue_number: prNumber, per_page: 100,
+  });
+  const prior = comments.filter(c =>
+    c.user.type === 'Bot' && c.body && c.body.includes(marker)
+  );
+
+  const cleanupBody = `${marker}\n## Preview\n\n_Preview deployments for this PR have been cleaned up._`;
+
+  if (mode === 'repost') {
+    for (const c of prior) {
+      try {
+        await github.graphql(
+          `mutation($id: ID!) {
+             minimizeComment(input: {subjectId: $id, classifier: OUTDATED}) {
+               minimizedComment { isMinimized }
+             }
+           }`,
+          { id: c.node_id },
+        );
+      } catch (e) {
+        core.warning(`Could not minimize comment ${c.id}: ${e.message}`);
+      }
+    }
+    if (prior.length) {
+      await github.rest.issues.createComment({
+        owner, repo, issue_number: prNumber, body: cleanupBody,
+      });
+    }
+  } else {
+    const existing = prior[0];
+    if (existing) {
+      await github.rest.issues.updateComment({
+        owner, repo, comment_id: existing.id, body: cleanupBody,
+      });
+    }
+  }
+};