docs: Prepare 1.2.0 release

[nfebe]

Cuts the 1.2.0 release, bringing the merged dependency-install work (#18) to main. Also switches the version marker to the standard version field.

[sourceant]

Code Review Summary

This release (1.2.0) introduces significant improvements to plugin dependency management, allowing plugins to declare and install their own Composer requirements. It also adds support for local path installations.

🚀 Key Improvements

• Added support for local path plugin installation via plugin:install.
• Automatic dependency resolution and installation from the plugin's composer.json.
• Integration with wikimedia/composer-merge-plugin for unified dependency trees.
• Standardized versioning using the version field in composer.json.

💡 Minor Suggestions

• Standardize json_decode with error handling.
• Clarify relative vs absolute path behavior in documentation.

[sourceant]

Review complete. See the overview comment for a summary.

[sourceant]

When parsing composer.json, it is safer to use JSON_THROW_ON_ERROR or handle potential nulls from json_decode more explicitly, though the subsequent check for is_array covers major failures.

Suggested change

	$manifest = json_decode((string) file_get_contents($composerFile), true);
	$manifest = json_decode((string) file_get_contents($composerFile), true, 512, JSON_THROW_ON_ERROR);

[sourceant]

Passing json_encode($repository) directly into a shell command via run can lead to shell injection or escaping issues if the repository URL or config contains special characters. Although Symfony\Component\Process handles array-to-string conversion, it is safer to ensure the input is sanitized or that json_encode flags prevent unexpected character interpretation.

Suggested change

	['composer', 'config', '--no-interaction', 'repositories.'.$repoName, json_encode($repository)],
	['composer', 'config', '--no-interaction', 'repositories.'.$repoName, json_encode($repository, JSON_UNESCAPED_SLASHES)],