fix(build): add server-schema.cpp to jllama_test sources (b9739 link fix)

The b9739 upgrade (#247) added tools/server/server-schema.cpp to the jllama
library target but not to the jllama_test executable target. server-schema.cpp
defines server_schema::eval_llama_cmpl_schema(), which test_server.cpp and the
upstream server-context.cpp reference, so the test link failed with an
undefined/unresolved external symbol on every platform that builds the tests
(Linux x86_64, macOS, Windows MSVC, Windows Ninja). The shared library itself
links fine — only jllama_test was missing the TU. Add server-schema.cpp to the
jllama_test source list, mirroring its presence in the library target.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01SfvSZ76NW4e1qX1PjL4RKq

Author: claude

CMakeLists.txt

@@ -408,6 +408,7 @@ if(BUILD_TESTING)
         ${llama.cpp_SOURCE_DIR}/tools/server/server-context.cpp
         ${llama.cpp_SOURCE_DIR}/tools/server/server-queue.cpp
         ${llama.cpp_SOURCE_DIR}/tools/server/server-task.cpp
+        ${llama.cpp_SOURCE_DIR}/tools/server/server-schema.cpp
         ${llama.cpp_SOURCE_DIR}/tools/server/server-models.cpp
     )