fix(codegen): declare cross-module method wrappers in consumer TU (#1126)

[proggeramlug]

Summary

Fixes #1126. Expr::SuperPropertyGet (value form const f = super.foo) emits js_closure_alloc_singleton(@__perry_wrap_<fn>) against the resolved parent method's wrapper. When the parent class lives in a different module — the common npm-package pattern where a derived class overrides hook methods on an imported parent (rxjs's OperatorSubscriber extends Subscriber, delegating `_next` / `_error` / `_complete` to `super`) — the wrapper's `define` is in the source class's LLVM TU, but the consumer TU never forward-declared the symbol. clang failed per-TU IR validation with:

error: use of undefined value '@__perry_wrap_perry_method_..._Subscriber___complete'

That cascaded: OperatorSubscriber.ts couldn't compile → the empty-stub fallback only emits the __init symbol (not class methods/constructors) → every downstream rxjs operator that referenced OperatorSubscriber::unsubscribe or its constructor failed to link (LNK2019 on MSVC, Undefined symbol on macOS ld). 226 modules succeeded, 1 failure, link death. The repro is the canonical 5-line rxjs Subject test from the issue body — every rxjs user hits this.

Fix

crates/perry-codegen/src/expr/mod.rs Expr::SuperPropertyGet: push (__perry_wrap_<fn>, double, [i64]) into pending_declares before emitting the singleton call.

LlModule::declare_function (module.rs:67) is dedupe-by-name and the comment explicitly notes:

If a function with the same name is later defined in this module, the declaration is dropped at to_ir time so LLVM doesn't see both.

So this is safe for the same-module case (the declaration is dropped, no duplicate symbol) and unblocks the cross-module case. Signature is informational per the existing pattern at expr/mod.rs:12331:

The signature is for LLVM-IR well-formedness only — the runtime closure-call machinery casts the func_ptr to its own ABI at dispatch time

Test plan

• Issue-body 5-line rxjs repro (import { Subject } from 'rxjs'; new Subject().subscribe(v => console.log(v)); .next(1)): pre-fix dies with Error compiling module 'OperatorSubscriber.ts' + 28 downstream LNK2019 undefined-symbol errors. Post-fix all 227 modules compile, link succeeds, the 2.0 MB binary prints 1.
• Same-module value-form super.foo smoke test (class B { greet(n){...} } class D extends B { f(n){ const g = super.greet; return g(n) } }) still prints Hello, world (the declare drops at to_ir time, no LLVM duplicate-symbol).
• cargo test --release -p perry-codegen clean
• cargo test --release --workspace --exclude perry-ui-... clean

The cascading link-error path from #1126's body (when ANY module fails to compile, the empty-stub fallback doesn't synthesize method/constructor symbols for downstream modules) is not separately fixed in this PR — but no longer fires because there's no failed-module to stub.