ci: add docs build workflow for @kilocode/kilo-docs

Adapted from kilocode repo's markdoc-build.yml:
- pnpm → bun (using shared setup-bun action)
- Path-filtered to only run on packages/kilo-docs changes
- Targets dev branch
- Includes both build and test steps

.github/workflows/docs-build.yml

@@ -0,0 +1,30 @@
+name: docs-build
+
+on:
+  push:
+    branches: [dev]
+    paths:
+      - "packages/kilo-docs/**"
+  pull_request:
+    paths:
+      - "packages/kilo-docs/**"
+  workflow_dispatch:
+
+jobs:
+  build:
+    name: Build docs site
+    runs-on: blacksmith-4vcpu-ubuntu-2404
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Setup Bun
+        uses: ./.github/actions/setup-bun
+
+      - name: Build site
+        run: bun run --filter @kilocode/kilo-docs build
+        env:
+          POSTHOG_API_KEY: ${{ secrets.POSTHOG_API_KEY }}
+
+      - name: Run tests
+        run: bun run --filter @kilocode/kilo-docs test