Cache Jekyll Picture Tag generated images in CI

[Copilot]

Jekyll Picture Tag regenerates optimized images on every CI run, wasting time processing unchanged assets.

Changes

• Added actions/cache@v4 step to active Jekyll build workflows (deploy.yml, deploy-pr-preview.yml)
• Removed obsolete build-jekyll.yaml workflow (integrated with latest deployment method from PR Remove deprecated deployment workflow #70)
• Cache path: generated/ directory where Jekyll Picture Tag outputs processed images
• Cache key: Hashed on assets/img/** and _data/picture.yml to invalidate when source images or config change
• Added generated/ to .gitignore

- name: Cache generated images
  uses: actions/cache@v4
  with:
    path: generated/
    key: ${{ runner.os }}-generated-images-${{ hashFiles('assets/img/**', '_data/picture.yml') }}
    restore-keys: |
      ${{ runner.os }}-generated-images-

Cache restores on subsequent runs when source images are unchanged, skipping expensive libvips processing.

This PR has been updated to integrate with the deployment method changes merged in PR #70, which removed the legacy build-jekyll.yaml workflow.

• Fixes Cache image builds in actions #67

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Cache image builds in actions</issue_title>
<issue_description>Rebuilding the image files in each action run is expensive and time consuming. Cache this folder across runs</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Cache image builds in actions #67

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[Copilot]

Pull Request Overview

This PR implements caching for Jekyll Picture Tag generated images across all CI workflows to avoid expensive regeneration of unchanged images on every build.

Key Changes:

• Added actions/cache@v4 step to cache the generated/ directory in all three Jekyll build workflows
• Cache key invalidates when source images (assets/img/**) or picture configuration (_data/picture.yml) change
• Added generated/ to .gitignore to exclude the cache directory from version control

Reviewed Changes

Copilot reviewed 3 out of 4 changed files in this pull request and generated no comments.

File	Description
.gitignore	Added generated/ directory to exclude Jekyll Picture Tag output from version control
.github/workflows/deploy.yml	Added image caching step and updated step numbering (Steps 3-6)
.github/workflows/deploy-pr-preview.yml	Added image caching step and updated step numbering (Steps 3-7) for PR preview builds
.github/workflows/build-jekyll.yaml	Added image caching step after existing dependency cache for the alternative build workflow

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[wintermuted]

@copilot this change needs to be integrated with the change in deployment method that was merged

[Copilot]

@copilot this change needs to be integrated with the change in deployment method that was merged

Integrated the caching changes with the latest deployment method. Removed the obsolete build-jekyll.yaml workflow and kept the caching configuration in the two active workflows (deploy.yml and deploy-pr-preview.yml).

Changes in commit 66d1021.

[github-actions]

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