The changes introduce a Tcl symbol index powering LSP navigation
features across the workspace. A navigation API exposes
snapshots and update hooks, enabling goto-definition,
references, and rename using the index. Background indexing
now watches Tcl files and rebuilds the index to stay in sync.
- Add Tcl symbol index and navigation snapshot API
- Wire go-to-definition, references, and rename using the index
- Watch Tcl files and refresh the index in the background
