feat(lsp): add incremental indexing and file ops support

Adds a thread-safe incremental index and snapshot API for LSP.
Introduces cache invalidation and file operation hooks for delete
and rename. This keeps indices in sync with disk changes.
Supports reindexing TCL files from disk when needed.

- Adds workspace file change handlers to sync indices on delete/rename.
- Introduces locking and snapshot helpers to safely access shared state.
- Refactors to invalidate caches on edits and reindex TCL files.

CHANGELOG.md

@@ -1,6 +1,8 @@
 ## Unreleased
 
 - Add signature help for custom TCL procedures and built-in NX/MOM procedures
+- Clean stale TCL indexes on close, delete, and rename operations
+- Make background parsing and index updates thread-safe
 
 ## [0.0.1]