Fix concurrent map write panic in timeout middleware

- Add thread-safe header wrapper in timeoutWriter
- Check context cancellation before writing responses in handlers
- Protect header access after timeout with mutex
- Prevents race condition when requests timeout while handlers are still running

Makefile

@@ -21,7 +21,7 @@ clean:
 	rm -rf bin/
 
 run: build
-	./bin/routewatch
+	DEBUG=routewatch ./bin/routewatch 2>&1 | tee log.txt
 
 asupdate:
 	@echo "Updating AS info data..."