- Pass extension storage path to the server (client/ changes) so the
server can persist a workspace index.
- Introduce IndexCache (server/tools/index_cache.py) and load/save it on
initialization and after background indexing. Index entries are stored
only when the file's stat hasn't changed while being read.
- Add incremental reparse logic (server/tools/incremental_parse.py) and
use a per-file _last_parse cache in the language server to reparse only
the top-level Tcl commands touched by an edit, falling back to a full
parse when necessary.
- Use a new _FileIndex dataclass and _build_file_index helper to unify
what is stored/loaded for a file; update update_poco_completion_for_file
to use the persistent cache for disk-read files (from_disk/source_stat).
- Keep background indexing non-blocking and persist the index at the
end of the run. Add basic unit tests for incremental parse and index cache.
Before: edits and background work always required full parsing of files
and no persistent cross-restart index. After: some edits reuse previous
ASTs and files read from disk can use a persisted index to skip
re-indexing across restarts.
