ci: auto-trigger main CI when tagging a Dependabot commit (#188)

* ci: auto-trigger main CI run when tagging a Dependabot commit

Dependabot auto-merges use GITHUB_TOKEN which GitHub intentionally does
not re-trigger other workflows on. This means tagging those commits
immediately fails the verify-prior-run gate.

Instead of hard-failing, trigger ci.yml on main and wait for it to
succeed before proceeding with the deploy. Only triggers once; detects
and surfaces failures from the triggered run.

Bumps actions permission from read to write to allow workflow dispatch.

* ci: address CodeRabbit feedback on verify-prior-run job

Reduce max_attempts from 40 to 30 so worst-case runtime (15m) fits within
the 20-minute job timeout with margin. Trigger the fallback workflow run on
the tag ref instead of main so the dispatched run's head_sha matches the
tagged commit SHA that the polling loop is checking for.

.github/workflows/ci.yml

@@ -166,7 +166,7 @@ jobs:
     timeout-minutes: 20
     if: startsWith(github.ref, 'refs/tags/')
     permissions:
-      actions: read
+      actions: write
     steps:
       - name: Wait for and verify successful CI run on this commit
         env:
@@ -174,6 +174,8 @@ jobs:
         run: |
           max_attempts=30
           attempt=0
+          triggered=false
+
           while [[ $attempt -lt $max_attempts ]]; do
             attempt=$((attempt + 1))
 
@@ -191,12 +193,32 @@ jobs:
               --jq "[.workflow_runs[] | select(.id != ${{ github.run_id }}) | select(.status == \"in_progress\" or .status == \"queued\" or .status == \"waiting\" or .status == \"requested\" or .status == \"pending\")] | length")
 
             if [[ "$in_progress_count" -gt 0 ]]; then
-              echo "CI still in progress (attempt $attempt/$max_attempts), waiting 30s..."
+              echo "CI in progress (attempt $attempt/$max_attempts), waiting 30s..."
               sleep 30
-            else
-              echo "::error::No prior successful CI run found for ${{ github.sha }}. Only tag commits that have passed CI on main."
+              continue
+            fi
+
+            if [[ "$triggered" == "false" ]]; then
+              echo "No prior CI run found for ${{ github.sha }}. Triggering CI on ${{ github.ref }}..."
+              gh workflow run ci.yml --repo "${{ github.repository }}" --ref "${{ github.ref }}"
+              triggered=true
+              echo "Triggered. Waiting 20s for run to register..."
+              sleep 20
+              continue
+            fi
+
+            failed_conclusion=$(gh api \
+              "repos/${{ github.repository }}/actions/workflows/ci.yml/runs?head_sha=${{ github.sha }}&per_page=10" \
+              --jq "[.workflow_runs[] | select(.id != ${{ github.run_id }}) | select(.status == \"completed\") | select(.conclusion != \"success\")] | first | .conclusion // empty" \
+              --raw-output)
+
+            if [[ -n "$failed_conclusion" ]]; then
+              echo "::error::Triggered CI run on main failed with conclusion: $failed_conclusion. Fix the issue before re-tagging."
               exit 1
             fi
+
+            echo "Waiting for triggered run to register (attempt $attempt/$max_attempts)..."
+            sleep 20
           done
 
           echo "::error::Timed out waiting for CI run to complete for ${{ github.sha }}."