`import models as m` aliases were stored in namedImportMap (a symbol-binding
map) then cross-referenced in pipeline.ts — semantic misuse and inefficient.
Refactored: NamedBinding gains `isModuleAlias` flag. applyImportResult routes
tagged bindings directly to moduleAliasMap at import time. Removes the
pipeline.ts post-processing loop entirely.
Added test fixture and 5 integration tests for `import X as Y` with
multi-module disambiguation (both models.py and auth.py export User).
