Fix GitHub Pages deployment workflow for branch builds

[Sendipad]

Motivation

• The Pages workflow only triggered for a fixed branch list and failed to deploy from other branches, and generated site URLs could be incorrect for GitHub project pages.
• In-progress Pages runs could produce stale deployments if not cancelled when re-run.

Description

• Change the workflow trigger to run on pushes from any branch by using branches: - "**" so branch builds will deploy.
• Add id: pages to the actions/configure-pages@v5 step and pass the Pages-provided base_url into Hugo via --baseURL "${{ steps.pages.outputs.base_url }}/" to produce correct URLs for project-site hosting.
• Enable Hugo garbage collection in the build step by adding --gc and keep --minify to reduce output size.
• Set workflow concurrency cancel-in-progress: true to avoid overlapping/stale Pages runs.

Testing

• Parsed .github/workflows/deploy.yml successfully using ruby -e 'require "yaml"; YAML.load_file(".github/workflows/deploy.yml"); puts "ok"' (passed).
• Attempted hugo version locally but hugo is not installed in this environment so the binary check failed; the CI workflow installs Hugo during run (so build will run in CI).

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Codex Task