refactor: Decoupling chat architecture (#367)

* refactor: Migrate tests to Qt Creator plugin framework and update llmqore transports

* refactor: Move conversation history into IDE-free session library

* refactor: Extract turn context assembly behind injected ports

* build: Add RunQodeAssistTests target for the plugin test suite

* refactor: Route the chat through a Session and ChatBackend seam

sources/session/CMakeLists.txt

@@ -0,0 +1,22 @@
+add_library(QodeAssistSession STATIC
+    ContentBlock.hpp
+    Message.hpp
+    ConversationHistory.hpp ConversationHistory.cpp
+    FileEditPayload.hpp FileEditPayload.cpp
+    HistoryProjection.hpp HistoryProjection.cpp
+    HistorySerializer.hpp HistorySerializer.cpp
+    SessionEvent.hpp SessionEvent.cpp
+    TurnRequest.hpp
+    ChatBackend.hpp
+    Session.hpp Session.cpp
+    TurnContext.hpp TurnContext.cpp
+    TurnContextPorts.hpp
+    TurnContextBuilder.hpp TurnContextBuilder.cpp
+)
+
+target_link_libraries(QodeAssistSession
+    PUBLIC
+    Qt::Core
+)
+
+target_include_directories(QodeAssistSession PUBLIC ${CMAKE_SOURCE_DIR}/sources)