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.

lsp/LspTypes.h

@@ -10,6 +10,10 @@
 #include <vector>
 
 namespace kte::lsp {
+// NOTE on coordinates:
+// - Internal editor coordinates use UTF-8 columns counted by Unicode scalars.
+// - LSP wire protocol uses UTF-16 code units for the `character` field.
+//   Conversions are performed in higher layers via `lsp/UtfCodec.h` helpers.
 struct Position {
 	int line      = 0;
 	int character = 0;