Plugin loading mechanism documented

When the plugin loading mechanism is undocumented, a developer who has built a working plugin cannot install it. They do not know whether to place files in a plugins/ directory, add an entry to a config file, or call a registration function. ISO 25010 maintainability.modularity requires that the extension point be clearly defined; an undocumented loading mechanism makes the extension point inaccessible despite technically existing. The barrier affects plugin users as much as plugin authors — a correctly built plugin that cannot be installed provides no value.

Document the full loading flow in src/plugins/README.md or docs/plugins.md, covering file placement, naming conventions, configuration entries, and activation sequence. Include a working import pattern.

// src/plugins/loader.ts — dynamic plugin loading
const plugins = await import(`./plugins/${name}/index.ts`);

Also document whether plugins can be hot-loaded after startup or require a restart.