feat: server log streaming via SSE for desktop log panel

- LogStreamService: singleton that extends ConsoleLogger, captures all
  NestJS log output into an RxJS Subject while preserving stdout
- main.ts: uses LogStreamService.instance as app logger
- supervisor.controller.ts: new @Sse('logs/stream') endpoint pipes
  log entries (timestamp, level, context, message) to connected clients

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

src/logging/log-stream.service.ts

@@ -0,0 +1,52 @@
+import { ConsoleLogger } from '@nestjs/common';
+import { Subject } from 'rxjs';
+
+export type LogEntry = {
+    timestamp: string;
+    level: 'log' | 'error' | 'warn' | 'debug' | 'verbose';
+    context: string;
+    message: string;
+};
+
+// Singleton — created once in main.ts, accessed by the SSE controller
+// via LogStreamService.instance. NestJS DI isn't available at bootstrap
+// time (the logger is created before the container), so we use a static
+// instance instead of @Injectable().
+export class LogStreamService extends ConsoleLogger {
+    static readonly instance = new LogStreamService();
+    readonly logSubject = new Subject<LogEntry>();
+
+    private emit(level: LogEntry['level'], message: unknown, context?: string) {
+        this.logSubject.next({
+            timestamp: new Date().toISOString(),
+            level,
+            context: context ?? this.context ?? '',
+            message: typeof message === 'string' ? message : JSON.stringify(message),
+        });
+    }
+
+    log(message: unknown, context?: string) {
+        super.log(message, context);
+        this.emit('log', message, context);
+    }
+
+    error(message: unknown, stack?: string, context?: string) {
+        super.error(message, stack, context);
+        this.emit('error', message, context);
+    }
+
+    warn(message: unknown, context?: string) {
+        super.warn(message, context);
+        this.emit('warn', message, context);
+    }
+
+    debug(message: unknown, context?: string) {
+        super.debug(message, context);
+        this.emit('debug', message, context);
+    }
+
+    verbose(message: unknown, context?: string) {
+        super.verbose(message, context);
+        this.emit('verbose', message, context);
+    }
+}

src/main.ts

@@ -3,9 +3,11 @@ import type { NestExpressApplication } from '@nestjs/platform-express';
 import { join } from 'path';
 import { AppModule } from './app.module';
 import { ConfigService } from '@nestjs/config';
+import { LogStreamService } from './logging/log-stream.service';
 
 async function bootstrap() {
-    const app = await NestFactory.create<NestExpressApplication>(AppModule);
+    const logger = LogStreamService.instance;
+    const app = await NestFactory.create<NestExpressApplication>(AppModule, { logger });
     const config = app.get(ConfigService);
 
     app.enableCors({

src/supervisor/supervisor.controller.ts

@@ -1,6 +1,7 @@
 import { Controller, Get, Post, Body, Query, Sse, Logger } from '@nestjs/common';
 import { Observable, filter, map } from 'rxjs';
 import { SupervisorService } from './supervisor.service';
+import { LogStreamService } from '../logging/log-stream.service';
 
 @Controller('api/supervisor')
 export class SupervisorController {
@@ -76,4 +77,14 @@ export class SupervisorController {
             } as MessageEvent)),
         );
     }
+
+    @Sse('logs/stream')
+    streamLogs(): Observable<MessageEvent> {
+        this.logger.log('[SSE] Log stream opened');
+        return LogStreamService.instance.logSubject.pipe(
+            map(entry => ({
+                data: JSON.stringify(entry),
+            } as MessageEvent)),
+        );
+    }
 }