feat(build.yml): add GitHub Actions workflow for building the project

This commit adds a new file `.github/workflows/build.yml` which contains the configuration for a GitHub Actions workflow named "Build". The workflow is triggered on push events to the `main` branch and manually through the workflow_dispatch event.

The workflow consists of two jobs: "Filter" and "Build". The "Filter" job checks for changes in specific files (`package.json` and `assets/**`) and sets an output variable `any_changed` to indicate if any of the files have changed.

The "Build" job is executed if the following conditions are met:
- The workflow is triggered on the `main` branch
- The repository is not a fork
- The "Filter" job has detected changes in the specified files

The steps in the "Build" job include:
- Checking out the repository
- Setting up Hugo with version 0.114.0 and extended mode
- Setting up pnpm version 8
- Getting the pnpm store directory and caching it
- Caching the Hugo resources directory
- Installing dependencies using pnpm
- Building the project using the `pnpm run build` command
- Pushing the built artifacts if the workflow was triggered by a merged pull request

.github/workflows/build.yml

@@ -0,0 +1,83 @@
+name: 'Build'
+on:
+  push:
+    branches:
+      - main
+  workflow_dispatch:
+
+permissions:
+  contents: write
+
+jobs:
+  filter:
+    runs-on: ubuntu-latest
+    name: Filter
+    outputs:
+      any_changed: ${{ steps.changed-files-specific.outputs.any_changed }}
+    steps:
+      - uses: actions/checkout@v3
+        with:
+          fetch-depth: 0
+
+      - name: Get changed files in scope
+        id: changed-files-specific
+        uses: tj-actions/changed-files@v40
+        with:
+          files: |
+            package.json
+            assets/**
+
+  build:
+    timeout-minutes: 30
+    runs-on: ubuntu-latest
+    name: Build
+    needs: [filter]
+    if: |
+      github.ref == 'refs/heads/main' &&
+      github.event.repository.fork == false &&
+      needs.filter.outputs.any_changed == 'true'
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Setup Hugo
+        uses: peaceiris/actions-hugo@v2
+        with:
+          hugo-version: '0.114.0'
+          extended: true
+
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v2
+        with:
+          version: 8
+
+      - name: Get pnpm store directory
+        id: pnpm-cache
+        run: echo "STORE_PATH=$(pnpm store path)" >> $GITHUB_OUTPUT
+
+      - name: Setup pnpm cache
+        uses: actions/cache@v3
+        with:
+          path: ${{ steps.pnpm-cache.outputs.STORE_PATH }}
+          key: ${{ runner.os }}-pnpm-store-${{ hashFiles('**/pnpm-lock.yaml') }}
+          restore-keys: ${{ runner.os }}-pnpm-store-
+
+      - name: Setup hugo cache
+        uses: actions/cache@v3
+        with:
+          path: ./exampleSite/resources
+          key: ${{ runner.os }}-hugo-
+
+      - name: Install dependencies
+        run: pnpm install
+
+      - name: Build
+        run: |
+          pnpm run build
+
+      - name: Push artifacts
+        if: ${{ github.event.pull_request.merged == true }}
+        run: |
+          git config --global user.email "noreply@github.com"
+          git config --global user.name "CI"
+          git diff --quiet || (git add -A && git commit -m "build: update bundled artifacts [skip ci]" && git push)