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
