feat(plugins): bridge core domain events to plugin event bus

The plugin event bus accepts subscriptions for core events like
issue.created but nothing emits them. This adds a bridge in
logActivity() so every domain action that's already logged also
fires a PluginEvent to subscribing plugins.

Uses a module-level setter (same pattern as publishLiveEvent)
to avoid threading the bus through all route handlers. Only
actions matching PLUGIN_EVENT_TYPES are forwarded.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

server/src/app.ts

@@ -37,6 +37,7 @@ import { pluginLifecycleManager } from "./services/plugin-lifecycle.js";
 import { createPluginJobCoordinator } from "./services/plugin-job-coordinator.js";
 import { buildHostServices, flushPluginLogBuffer } from "./services/plugin-host-services.js";
 import { createPluginEventBus } from "./services/plugin-event-bus.js";
+import { setPluginEventBus } from "./services/activity-log.js";
 import { createPluginDevWatcher } from "./services/plugin-dev-watcher.js";
 import { createPluginHostServiceCleanup } from "./services/plugin-host-service-cleanup.js";
 import { pluginRegistryService } from "./services/plugin-registry.js";
@@ -141,6 +142,7 @@ export async function createApp(
   const workerManager = createPluginWorkerManager();
   const pluginRegistry = pluginRegistryService(db);
   const eventBus = createPluginEventBus();
+  setPluginEventBus(eventBus);
   const jobStore = pluginJobStore(db);
   const lifecycle = pluginLifecycleManager(db, { workerManager });
   const scheduler = createPluginJobScheduler({