ci: QA suite (repo+live), Gitea Actions workflow, app config-as-code

- qa/site-qa.sh: repo structure/link checks + full live crawl (routes,
  links, assets, canonical-https)
- .gitea/workflows/qa.yml: repo QA on push, nightly live QA
- app/: config-as-code for the deployed sync job, scheduler entry,
  and Grav system.yaml (reverse-proxy HTTPS detection)
- local pre-push hook runs repo QA

https://projects.knownelement.com/issues/928

.gitea/workflows/qa.yml

@@ -0,0 +1,24 @@
+name: QA
+on:
+  push:
+  workflow_dispatch:
+  schedule:
+    - cron: '0 9 * * *'   # 09:00 UTC nightly live QA
+
+jobs:
+  repo-qa:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Repo checks (structure, frontmatter, link targets)
+        run: ./qa/site-qa.sh
+
+  live-qa:
+    runs-on: ubuntu-latest
+    if: github.event_name == 'schedule' || github.event_name == 'workflow_dispatch'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+      - name: Live checks (STLP site routes, links, canonical)
+        run: ./qa/site-qa.sh -l https://startinglineproductions.com