BUG-1: Extract PLUGIN_REGISTRY to plugin.tokens.ts to break ESM
circular reference between plugin.module.ts and plugin.service.ts.
Was causing ReferenceError at startup.
BUG-2: Replace AuthStorage.create() with AuthStorage.inMemory() in
ProviderService. The file-based auth storage resolves ~/.pi/auth.json
which causes silent process exit in server context.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>