fix(resolution): keep unknown Python import members unresolved (#2040)

Bisect identifies 5eaa6fed (#2034, #1820) as the first bad commit: its Python named-import fallback resolves task.delay() to the task function itself, hiding the queue effect in API steps. Require member resolution before returning a named Python import's target for attribute access.

Keep direct calls, callbacks, constructors, and known members working. Add absolute/relative aliased-import regression coverage without changing the existing steps assertions.

Validation: git bisect with preserved steps test, tsc and copy-assets at every step, CODEGRAPH_KERNEL=0 throughout bisect. 338 tests pass across ui-steps-api-servers, function-ref, rebuilt kernel-tsjs-parity, resolution, and ui-effects. Issue #1820 repro and tsc --noEmit pass.

src/resolution/import-resolver.ts

@@ -1725,6 +1725,13 @@ export function resolveViaImport(
             // constant edge below rather than fabricating a wrong one.
             const instanceMember = resolveImportedInstanceMember(targetNode, ref, imp.localName, context);
             if (instanceMember) return instanceMember;
+
+            // Finding a named Python import proves the receiver exists, not
+            // its requested attribute. In particular, task.delay() enqueues
+            // work; it does not call the imported task function directly.
+            // Keep unknown members unresolved (including callback values)
+            // instead of falling back to the receiver as their target.
+            if (ref.language === 'python') return null;
           }
 
           return {