Thin client extension: registers the forester language for .tree files,
starts the LSP server over stdio, and gets semantic-token highlighting,
completion, comment toggling, and bracket matching.
Supported features
Language-server features (from forester-lsp):
Syntax highlighting via LSP semantic tokens
Diagnostics — parse errors reported inline as you type
Completion — triggered on ", /, and .
Go to definition
Find references
Document symbols — outline / breadcrumbs for tree nodes
Formatting (Format Document)
Editor features (from the language configuration):
Comment toggling — // line comments and /* */ block comments
Bracket matching and auto-closing for {}, [], (), and strings
