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/TurnContextBuilder.cpp

@@ -0,0 +1,58 @@
+// Copyright (C) 2026 Petr Mironychev
+// SPDX-License-Identifier: GPL-3.0-or-later
+// Additional attribution terms under GPLv3 §7(b) apply — see LICENSE
+
+#include "session/TurnContextBuilder.hpp"
+
+#include <QRegularExpression>
+#include <QStringList>
+
+namespace QodeAssist::Session {
+
+TurnContextBuilder::TurnContextBuilder(
+    const IProjectContextPort &project,
+    const ISkillsContextPort *skills,
+    const ILinkedFilesPort &linkedFiles)
+    : m_project(project)
+    , m_skills(skills)
+    , m_linkedFiles(linkedFiles)
+{}
+
+TurnContext TurnContextBuilder::build(const TurnContextRequest &request) const
+{
+    TurnContext context;
+    context.basePrompt = request.basePrompt;
+    context.rolePrompt = request.rolePrompt;
+
+    context.project = m_project.projectInfo();
+    if (context.project.available)
+        context.projectRules = m_project.projectRules();
+
+    if (m_skills) {
+        context.alwaysOnSkills = m_skills->alwaysOnBodies();
+        context.skillsCatalog = m_skills->catalogText();
+
+        static const QRegularExpression skillCommand(
+            QStringLiteral("(?:^|\\s)/([a-z0-9][a-z0-9-]*)"));
+        QStringList invokedSkillNames;
+        auto skillMatch = skillCommand.globalMatch(request.message);
+        while (skillMatch.hasNext()) {
+            const QString skillName = skillMatch.next().captured(1);
+            if (invokedSkillNames.contains(skillName))
+                continue;
+            const auto invokedSkill = m_skills->findSkill(skillName);
+            if (invokedSkill && !invokedSkill->body.isEmpty()) {
+                invokedSkillNames << skillName;
+                context.invokedSkills.append(*invokedSkill);
+            }
+        }
+    }
+
+    context.linkedFilePaths = request.linkedFilePaths;
+    if (!request.linkedFilePaths.isEmpty())
+        context.linkedFiles = m_linkedFiles.readFiles(request.linkedFilePaths);
+
+    return context;
+}
+
+} // namespace QodeAssist::Session