Summary

• Stacked on top of feat: tree-shake export default <namespace> re-exports #9574. Extends the export default <namespace> re-export tree-shaking to named variable exports of the form export <kind> res = ns;, where ns is an import * as ns local.
• Drops the const-only outer gate in favor of SymbolRefFlags::IsNotReassigned on the declared binding — let/var qualify whenever they have no write references, matching the safety property exactly.
• When the binding is provably non-reassignable and its initializer is a bare namespace identifier, LocalExport[name].referenced is rewired to the namespace local. The re-export chain in bind_imports_and_exports then propagates downstream, enabling member-expression tree-shaking through res.

REPL repro that motivated this

// middle.js
import * as api from "./api";
export const res = api;

// main.js
import { res } from "./middle";
console.log(res.used);  // `unused` should be tree-shaken — wasn't, before this

Output before: full api_exports namespace object + both used and unused kept. Output after: collapses to console.log("used").

Test plan

• named_const_export_namespace — basic case from the REPL link
• named_const_export_namespace_member_write — res.obj.a = 2 resolves through to the underlying binding, matching default_export_namespace_member_write
• named_let_export_namespace — let with no writes optimizes identically to const
• named_let_export_namespace_reassigned — let res = api; res = {...} keeps the namespace and respects the post-reassignment value
• All 1735 integration tests pass