fix: install optionalDependencies

[davideicardi]

FIX: #97

• install optional dependencies like npm, see https://docs.npmjs.com/cli/v11/configuring-npm/package-json#optionaldependencies
• handle install errors gracefully
• update readme to mention optional dependency support
• test optional dependency installation and failure cases

[Copilot]

Pull Request Overview

Adds support for optionalDependencies in plugin installation by extending the core managers, updating tests, and documenting the new behavior.

• Extend VersionManager and PluginManager to detect and install optional dependencies (ignoring failures).
• Add end-to-end tests for successful and failed optional dependency installation.
• Bump version to 1.1.0 and update README to mention optional dependency support.

Reviewed Changes

Copilot reviewed 20 out of 20 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
test/my-plugin-with-opt-dep/package.json	Defines an optional dependency for test plugin
test/my-plugin-with-opt-dep/index.js	Uses moment to verify optional dep installation
test/my-plugin-with-bad-opt-dep/package.json	Defines a non-existent optional dependency
test/my-plugin-with-bad-opt-dep/index.js	Simple export to verify install continues on failure
test/PluginManagerSuite.ts	Adds TypeScript tests for optional dependencies
test/PluginManagerSuite.js	Adds JavaScript tests and location assertions
src/VersionManager.ts	Captures optionalDependencies from package.json
src/PluginManager.ts	Refactors dependency installation to include optional deps
src/PluginInfo.ts	Updates plugin info interface with optional deps
src/PackageInfo.ts	Updates package info interface with optional deps
package.json	Bumps package version to 1.1.0
README.md	Documents optional dependency support