stem95su: scheduled Drive->site sync CronJob (every 10m)

CronJob stem95su-gdrive-sync (*/10) mounts the content PVC RW and
rclone-syncs the read-only Drive folder "claude" (stem claude/files) onto
it (rclone/rclone:1.74.3, scope=drive.readonly, empty-source guard +
--max-delete 25). ESO ExternalSecret stem95su-rclone <- Vault
secret/stem95su. Requires the GCP OAuth app published to Production or the
refresh token expires ~weekly.

Lands the gdrive-sync stack on master (it had landed on a feature branch
by accident on the shared devvm checkout).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

.github/workflows/deploy-postmortems.yml

@@ -1,32 +0,0 @@
-name: Deploy Post-Mortems to GitHub Pages
-
-on:
-  push:
-    branches: [master]
-    paths:
-      - 'post-mortems/**'
-  workflow_dispatch:
-
-permissions:
-  contents: read
-  pages: write
-  id-token: write
-
-concurrency:
-  group: pages
-  cancel-in-progress: false
-
-jobs:
-  deploy:
-    environment:
-      name: github-pages
-      url: ${{ steps.deployment.outputs.page_url }}
-    runs-on: ubuntu-latest
-    steps:
-      - uses: actions/checkout@v4
-      - uses: actions/configure-pages@v5
-      - uses: actions/upload-pages-artifact@v3
-        with:
-          path: post-mortems
-      - id: deployment
-        uses: actions/deploy-pages@v4