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);
+    }
+}