feat(plugins): show plugin logs on detail page via Docs/Logs tablist

Add a Logs tab beside Documentation on the plugin detail page, showing
the output a plugin prints through the standard Python logger (per the
wiki style guide). Logs are captured from the plugin's stderr by the
plugin runtime and fetched on demand.

- Bump langbot-plugin pin to 0.4.4 (adds GET_PLUGIN_LOGS action)
- plugin_connector/handler: get_plugin_logs RPC client
- HTTP route GET /api/v1/plugins/<author>/<name>/logs (limit + level)
- Frontend: wrap detail right panel in Docs/Logs Tabs; PluginLogs
  component with level filter, manual + 3s auto refresh, bottom-follow
- i18n: 7 new keys across all 8 locales

web/src/app/infra/entities/plugin/index.ts

@@ -21,6 +21,13 @@ export interface PluginComponent {
   };
 }
 
+// A single log line captured from a running plugin's stderr.
+export interface PluginLogEntry {
+  ts: number;
+  level: string;
+  text: string;
+}
+
 // marketplace plugin v4
 export enum PluginV4Status {
   Any = 'any',