When a project is opened for the first time (e.g. right after
create_project) the sym-lib-table may not exist on disk yet.
SymbolLibraryManager.__init__ succeeds but leaves self.libraries={}.
The original guard in use_project() was:
if self.library_manager.project_path == project_path:
return
Because the path already matched the newly-created manager, the
early-return fired and the manager was never rebuilt once the
sym-lib-table appeared. All subsequent list_symbols / search calls
returned nothing.
Fix: also require that at least one library was loaded before
treating the cache as valid.
Adds three unit tests that cover:
- rebuild triggered when project_path matches but libraries={}
- no spurious rebuild when libraries are already loaded
- rebuild on project_path change (existing behaviour)
