Add manual "down" infrastructure workflow trigger and AWS credentials…

.github/workflows/teardown_infrastructure.yaml

@@ -3,14 +3,23 @@ name: Teardown infrastructure
 on:
   schedule:
     - cron: 0 23 * * 1-5
+  workflow_dispatch:
 jobs:
   teardown_infrastructure:
     name: Teardown infrastructure on weekday schedule
     runs-on: ubuntu-latest
     environment: pulumi
+    permissions:
+      id-token: write
+      contents: read
     steps:
       - name: Checkout code
         uses: actions/checkout@v4
+      - name: Configure AWS credentials
+        uses: aws-actions/configure-aws-credentials@v5
+        with:
+          role-to-assume: ${{ secrets.AWS_IAM_INFRASTRUCTURE_ROLE_ARN }}
+          aws-region: ${{ secrets.AWS_REGION }}
       - name: Install Flox
         uses: flox/install-flox-action@v2
       - name: Dismantle with Pulumi

infrastructure/Pulumi.production.yaml

@@ -0,0 +1,3 @@
+config:
+  aws:region:
+    secure: AAABALPeEekY8m4V3bzTX5idnUTmjjjRWfJQit7uhk+w4mxTWyDK5r0=