feat: add support acp in common chat (#369)

sources/session/FencedText.cpp

@@ -0,0 +1,36 @@
+// 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/FencedText.hpp"
+
+namespace QodeAssist::Session {
+
+namespace {
+
+constexpr int minimumFenceLength = 3;
+
+int longestBacktickRun(const QString &content)
+{
+    int longest = 0;
+    int current = 0;
+
+    for (const QChar character : content) {
+        current = character == QLatin1Char('`') ? current + 1 : 0;
+        longest = qMax(longest, current);
+    }
+
+    return longest;
+}
+
+} // namespace
+
+QString fencedFileBlock(const QString &fileName, const QString &content)
+{
+    const int fenceLength = qMax(minimumFenceLength, longestBacktickRun(content) + 1);
+    const QString fence(fenceLength, QLatin1Char('`'));
+
+    return QStringLiteral("File: %1\n%2\n%3\n%2").arg(fileName, fence, content);
+}
+
+} // namespace QodeAssist::Session