add ublk loop server example

docs/examples.md

@@ -20,5 +20,8 @@
 - [queue-kernel-futex.cpp](queue-kernel-futex_8cpp_source.html)
     Builds a producer-consumer queue through asynchronous futex syscalls (`condy::async_futex_wait()`), implementing an asynchronous semaphore for synchronization.
 
+- [ublk-loop.cpp](ublk-loop_8cpp_source.html)
+    A ublk loop block device server using `condy::async_uring_cmd`. Coroutines make the ublk server logic easy to follow.
+
 - [module-hello.cpp](module-hello_8cpp_source.html)
     Demonstrates using Condy as a C++20 module via `import condy;`. Requires CMake 3.28+, Ninja, and GCC 14+ or Clang 16+. Build with `-DBUILD_MODULE=ON`.

examples/CMakeLists.txt

@@ -16,6 +16,9 @@ target_link_libraries(queue-kernel-futex PRIVATE condy uring)
 add_executable(queue-condy-futex queue-condy-futex.cpp)
 target_link_libraries(queue-condy-futex PRIVATE condy uring)
 
+add_executable(ublk-loop ublk-loop.cpp)
+target_link_libraries(ublk-loop PRIVATE condy uring)
+
 if(BUILD_MODULE)
     add_executable(module-hello module-hello.cpp)
     target_link_libraries(module-hello PRIVATE condy_module uring)