fix: avoid unnecessary didOpen/didClose LSP calls for cached files in full symbol tree

request_full_symbol_tree was opening every file in the language server
(sending didOpen + didClose notifications) even when document symbols
were already cached. For a ~600 file Kotlin project, this caused 1198
unnecessary pipe writes to the LSP process, taking ~9 seconds.

By passing open_in_ls=False, files are only read locally for cache
validation. The LSP is only notified when a cache miss requires
re-parsing. This reduces full-project symbol tree time from ~9.5s
to ~0.5s (19x improvement) on cached runs.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/solidlsp/ls.py

@@ -1406,7 +1406,7 @@ class SolidLanguageServer(ABC):
                         child["parent"] = package_symbol
 
                 elif os.path.isfile(contained_dir_or_file_abs_path):
-                    with self._open_file_context(contained_dir_or_file_rel_path) as file_data:
+                    with self._open_file_context(contained_dir_or_file_rel_path, open_in_ls=False) as file_data:
                         document_symbols = self.request_document_symbols(contained_dir_or_file_rel_path, file_data)
                         file_root_nodes = document_symbols.root_symbols