Refactor: Update asset handling to use Page Bundles

[zihanKuang]

Notes for Reviewers

This PR fixes #91

The goal is to change how asset URLs for banners and badges are handled in the theme. The previous method used the /static directory. This update moves the implementation to the Page Bundle model to create consistent behavior for all assets.

Summary of Changes

The implementation includes the following changes:

• Replaced Asset Logic

  • The old banner-url.html partial has been deleted.
  • A new partial, resolve-local-resource.html, has been added. It finds local asset paths within a Page Bundle and returns an absolute permalink.

• Updated Partials

  • All layouts that previously used banner-url.html (learning-path.json.html, common-curricula-properties.html, badge.html) have been refactored to use the new partials.
  • The badge.html partial retains its original function to support both remote URLs and local file paths. The local path logic is now handled by the new resolve-local-resource.html partial.

• Bug Fix

  • Fixed a bug in badge.html where the PNG image path was incorrectly referencing the SVG variable. It now correctly references the PNG variable.

Relevant docs PR for banner update: layer5io/docs#758 (merged)
Relevant schema PR for banner update: meshery/schemas#399

The changes are incompatible with the existing format. The original content needs to be modified before the relevant PRs can be merged.

[zihanKuang]

This is the test I performed:

• Case 1: Learning Path with a valid local banner

  • Setup: The Exoscale 101 learning path has banner: "exoscale-icon.svg" in its front matter, and the image file exists in its page bundle.
  • Result: The JSON output correctly contains the full, absolute permalink for the banner.

    "banner": "https://cloud.layer5.io/academy/learning-paths/orgID/exoscale-101/exoscale-icon.svg"

• Case 2: Nested Course with a valid local banner

  • Setup: The nested Exoscale - Advanced course also correctly references an image in its page bundle (banner: "exoscale-icon.svg").
  • Result: The logic successfully resolves the banner URL for the nested content.

    "banner": "https://cloud.layer5.io/academy/learning-paths/orgID/exoscale-101/advanced-course/exoscale-icon.svg"

• Case 3: Content with an invalid path

  • Setup: The End-to-End Kubernetes learning path references its banner using a subdirectory (banner: "images/exoscale-icon.svg"), which doesn't exist.
  • Result: The system correctly fails to find the resource and returns an empty string, ensuring the JSON output remains valid.

    "banner": ""