ci: migrate semver check labeller to ci labeller

diff --git a/.github/workflows/ci-labeller.yml b/.github/workflows/ci-labeller.yml
index e210a188..00f73f82 100644
--- a/.github/workflows/ci-labeller.yml
+++ b/.github/workflows/ci-labeller.yml
@@ -1,5 +1,5 @@
-# This workflow is triggered on completion of a CI job. It handles adding
-# labels to the PR which triggered the job. It is a separate workflow from
+# This workflow is triggered on completion of CI and semver check jobs. It handles adding
+# labels and comments to the PR which triggered the job. It is a separate workflow from
 # the CI workflow itself in order to follow security best practices.
 #
 # Since only workflows on the default branch (`master`) can be triggered, this
@@ -9,7 +9,7 @@
 
 on:   # yamllint disable-line rule:truthy
   workflow_run:  # zizmor: ignore[dangerous-triggers]
-    workflows: [Continuous integration]
+    workflows: [Continuous integration, Check semver breaks]
     types: [completed]
 
 name: CI Labeller
@@ -40,3 +40,12 @@ jobs:
           exit_code=$(tail -n1 api-diff)
           toggle=$([ "$exit_code" -eq 0 ] && echo "--remove-label" || echo "--add-label")
           gh pr edit $issue_number $toggle "API diff"
+      # The semver break artifact must have the PR number on the first line.
+      - name: "Comment and Label on API break"
+        if: ${{ hashFiles('semver-break') != '' }}
+        env:
+          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          issue_number=$(cat semver-break)
+          gh pr comment $issue_number --body 'API BREAKING CHANGE DETECTED!'
+          gh pr edit $issue_number --add-label "API break"
diff --git a/.github/workflows/semver-checks-pr-label.yml b/.github/workflows/semver-checks-pr-label.yml
deleted file mode 100644
index 2b1138ce..00000000
--- a/.github/workflows/semver-checks-pr-label.yml
+++ /dev/null
@@ -1,88 +0,0 @@
-on:   # yamllint disable-line rule:truthy
-  workflow_run:  # zizmor: ignore[dangerous-triggers]
-    workflows: [Check semver breaks]
-    types: [completed]
-
-name: Check semver breaks - Label and Comment PR
-
-permissions: {}
-
-jobs:
-  Download:
-    name: Download, Unzip and Add Labels/Comments
-    runs-on: ubuntu-24.04
-    permissions:
-      actions: read
-      contents: read
-      pull-requests: write
-    # only run if CI passes on the "Check semver breaks" workflow
-    if: ${{ github.event.workflow_run.conclusion == 'success' }}
-    steps:
-      - name: "Download artifact"
-        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
-        with:
-          script: |
-            // get all artifacts from the workflow run
-            let allArtifacts = await github.rest.actions.listWorkflowRunArtifacts({
-               owner: context.repo.owner,
-               repo: context.repo.repo,
-               run_id: context.payload.workflow_run.id,
-            });
-
-            // find the artifact that starts with 'semver-break'
-            let matchArtifact = allArtifacts.data.artifacts.filter((artifact) => {
-              return artifact.name.startsWith('semver-break');
-            })[0];
-
-            // if no artifact found, exit
-            if (!matchArtifact) {
-              console.log('No semver-break artifact found');
-              process.exit(0);
-            }
-
-            // otherwise download the artifact
-            let download = await github.rest.actions.downloadArtifact({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              artifact_id: matchArtifact.id,
-              archive_format: 'zip',
-            });
-
-            // write the artifact to the workspace
-            let fs = require('fs');
-            fs.writeFileSync(`${process.env.GITHUB_WORKSPACE}/semver-break.zip`, Buffer.from(download.data));
-      - name: "Unzip artifact"
-        if: ${{ hashFiles('semver-break.zip') != '' }}
-        run: unzip -n semver-break.zip
-      - name: "Comment and add label on PR - Semver break"
-        uses: actions/github-script@3a2844b7e9c422d3c10d287c895573f7108da1b3 # v9.0.0
-        if: ${{ hashFiles('semver-break') != '' }}
-        with:
-          github-token: ${{ secrets.GITHUB_TOKEN }}
-          script: |
-            // sanitize and get the PR number from the semver-break file
-            const fs = require('fs');
-            let issue_number = parseInt(fs.readFileSync('semver-break', 'utf8'), 10);
-
-            // assure that is not NaN using Number.isNaN
-            // since does not coerce the value to a number like isNaN
-            if (Number.isNaN(issue_number)) {
-              console.log('PR_NUMBER is not a number');
-              process.exit(1);
-            }
-
-            // comment on the PR
-            await github.rest.issues.createComment({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              issue_number: issue_number,
-              body: ':rotating_light: API BREAKING CHANGE DETECTED\n\nTo see the changes click details on "Continuous integration / Check (api)" job then expand "Run api" and scroll to the end of the section.'
-            });
-
-            // add the label to the PR
-            await github.rest.issues.addLabels({
-              owner: context.repo.owner,
-              repo: context.repo.repo,
-              issue_number: issue_number,
-              labels: ['API break']
-            });