Feat: validate domains are alive (and w/ CI)

.github/workflows/check-source-domain.yml

@@ -0,0 +1,24 @@
+name: Check Domain Availability
+on:
+  # manual trigger only
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build
+    runs-on: ubuntu-latest
+
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v4
+        with:
+          persist-credentials: false
+      - uses: pnpm/action-setup@v4
+        with:
+          run_install: false
+      - uses: actions/setup-node@v4
+        with:
+          node-version-file: ".node-version"
+          cache: "pnpm"
+      - run: pnpm install
+      - run: pnpm run node Build/validate-domain-alive.ts