fix: changelog-host parameter ignored when using manifest configuration

[vincentclee]

Problem

The changelog-host action parameter was being ignored when using manifest configuration files (release-please-config.json). This caused changelog links to always point to github.com instead of the specified GitHub Enterprise Server URL, breaking changelog functionality for GitHub Enterprise users.

Root Cause

The original implementation attempted to pass changelogHost through manifestOverrides to the Manifest.fromManifest() method. However, changelogHost is not part of the ManifestOptions interface - it belongs to the per-path ReleaserConfig interface. This architectural mismatch meant the parameter was silently ignored.

Solution

Modified the loadOrBuildManifest() function to:

1. Load the manifest normally without trying to pass changelogHost through manifest options
2. Post-process the loaded manifest to override changelogHost for all configured paths when the action input is provided and differs from the default GitHub URL

Technical Details

• Before: Attempted to use manifestOverrides.changelogHost (invalid approach)
• After: Directly modifies manifest.repositoryConfig[path].changelogHost for each path after manifest loading
• Only applies the override when changelog-host input is provided and differs from https://github.com
• Preserves existing behavior for config-less operation (single package repos)

Testing

• Updated existing test to verify the new implementation approach
• Maintains backward compatibility with all existing functionality
• Fixes the specific issue where GitHub Enterprise users couldn't customize changelog host URLs

Impact

This fix enables GitHub Enterprise Server users to properly use the changelog-host parameter with manifest configurations, ensuring changelog links point to their custom Git hosting instead

[google-cla]

Thanks for your pull request! It looks like this may be your first contribution to a Google open source project. Before we can look at your pull request, you'll need to sign a Contributor License Agreement (CLA).

View this failed invocation of the CLA check for more information.

For the most up to date status, view the checks section at the bottom of the pull request.

[ferrarimarco]

Thanks for this PR, a couple of things to check.

[ferrarimarco]

Thanks!