slang-server drops source locations for edited modules until save

Observed with slang-server 0.3.1 (SystemVerilog LSP): after any unsaved textDocument/didChange to a file, even whitespace only, scope or symbol queries return that file's module items without locations (empty uri, fromExpansion true). Named enum typedefs from it can't be resolved, and an unsaved package edit makes that package's types disappear from reads. After didSave and the next publishDiagnostics, reads are correct again. So a cache of LSP-derived type info should not be refreshed on every recompile after an edit, because that wipes it on each keystroke. Refresh it after a save (wait for the first diagnostics report after didSave, with a timeout fallback) and on external data reloads. Treat location-less results as 'unsaved, keep old data' rather than as 'no types'.