docs: move the reference site to astro starlight (#2527)

.github/workflows/build-docs.yaml

@@ -33,5 +33,4 @@ jobs:
     with:
       image: fluxer-docs
       dockerfile: fluxer_docs/Dockerfile
-      context: fluxer_docs
       build-version: ${{ inputs['build-version'] }}

.github/workflows/tests.yaml

@@ -460,6 +460,31 @@ jobs:
             exit 1
           fi
 
+  docs:
+    runs-on: ubuntu-24.04
+    timeout-minutes: 15
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0
+
+      - name: Install pnpm
+        uses: pnpm/action-setup@0ebf47130e4866e96fce0953f49152a61190b271
+
+      - name: Install Node.js
+        uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e
+        with:
+          node-version: '24'
+          cache: 'pnpm'
+
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile --filter fluxer_docs...
+
+      - name: Verify documentation matches the live API
+        run: pnpm --filter fluxer_docs verify
+
+      - name: Build documentation
+        run: pnpm --filter fluxer_docs build
+
   fonts:
     runs-on: ubuntu-24.04
     timeout-minutes: 10