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.

syntax/NullHighlighter.cc

@@ -0,0 +1,17 @@
+#include "NullHighlighter.h"
+#include "../Buffer.h"
+
+namespace kte {
+void
+NullHighlighter::HighlightLine(const Buffer &buf, int row, std::vector<HighlightSpan> &out) const
+{
+	const auto &rows = buf.Rows();
+	if (row < 0 || static_cast<std::size_t>(row) >= rows.size())
+		return;
+	std::string s = static_cast<std::string>(rows[static_cast<std::size_t>(row)]);
+	int n         = static_cast<int>(s.size());
+	if (n <= 0)
+		return;
+	out.push_back({0, n, TokenKind::Default});
+}
+} // namespace kte