Add SQL, Erlang, and Forth highlighter implementations and tests for LSP process and transport handling.

- Added highlighters for new languages (SQL, Erlang, Forth) with filetype recognition.
- Updated and reorganized syntax files to maintain consistency and modularity.
- Introduced LSP transport framing unit tests and JSON decoding/dispatch tests.
- Refactored `LspManager`, integrating UTF-16/UTF-8 position conversions and robust diagnostics handling.
- Enhanced server start/restart logic with workspace root detection and logging to improve LSP usability.

Buffer.h

@@ -14,7 +14,7 @@
 #include "UndoSystem.h"
 #include <cstdint>
 #include <memory>
-#include "HighlighterEngine.h"
+#include "syntax/HighlighterEngine.h"
 #include "Highlight.h"
 
 // Forward declarations to avoid heavy includes