feat: initial ZIPAIR Singapore sale monitor

Polls ZIPAIR sitemap every 10 min via Gitea Actions, detects new
Singapore/winter notifications, and fires an ntfy push alert.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

.gitea/workflows/zipair-monitor.yml

@@ -0,0 +1,41 @@
+name: ZIPAIR Singapore Sale Monitor
+
+on:
+  schedule:
+    # Runs every 10 minutes (cron is UTC)
+    - cron: '*/10 * * * *'
+  workflow_dispatch:   # allow manual trigger from Gitea UI
+
+jobs:
+  check:
+    runs-on: ubuntu-latest   # or your self-hosted runner label
+
+    steps:
+      - name: Checkout repo
+        uses: actions/checkout@v4
+        with:
+          # Need write access to commit state file back
+          token: ${{ secrets.GITEA_TOKEN }}
+
+      - name: Set up Python
+        uses: actions/setup-python@v5
+        with:
+          python-version: '3.11'
+
+      # No pip deps needed — script uses stdlib only
+
+      - name: Run ZIPAIR monitor
+        env:
+          NTFY_URL:   ${{ secrets.NTFY_URL }}
+          NTFY_TOKEN: ${{ secrets.NTFY_TOKEN }}
+          STATE_FILE: last_seen.txt
+        run: python check_zipair.py
+
+      - name: Commit updated state
+        run: |
+          git config user.name  "zipair-bot"
+          git config user.email "zipair-bot@localhost"
+          git add last_seen.txt
+          # Only commit if the file actually changed
+          git diff --cached --quiet || git commit -m "chore: update last_seen to $(cat last_seen.txt)"
+          git push