fix(compile): PerryTS/storekit#1 — route FFI imports through manifest path

[proggeramlug]

Summary

Closes PerryTS/storekit#1. Imports from a package declaring perry.nativeLibrary (e.g. @perryts/storekit) carry ambient export declare function signatures only — the real implementation lives in the linked static library. The compile-side import loop was unconditionally registering every named/default specifier in import_function_prefixes, which made lower_call.rs emit a call against perry_fn_<src>__<name> for symbols whose source module never emits that wrapper (no body to compile). Result: link failure (Undefined symbols: _perry_fn_..._js_storekit_start_listener), or — on older Perry builds where the codegen path differed — an LLVM IR verifier error reporting use of undefined value '@js_storekit_*' because the call was emitted with no matching declare.

Fix: when the import source matches a perry.nativeLibrary package and the specifier's exported name is listed in perry.nativeLibrary.functions, skip the import_function_prefixes registration. lower_call.rs then falls through to the FFI-manifest path (ctx.ffi_signatures), which emits a direct call to the declared FFI symbol along with a matching declare external at the top of the caller IR. The native-library lookup is pre-computed once per import (outside the per-specifier loop) so the check is constant-time.

Before / after

main.ts:

import { js_storekit_start_listener } from \"@perryts/storekit\";
js_storekit_start_listener();

Before:

Undefined symbols for architecture arm64:
  \"_perry_fn_node_modules__perryts_storekit_src_index_ts__js_storekit_start_listener\", referenced from:
      _main in main_ts.o

After (caller IR):

declare void @js_storekit_start_listener()
...
call void @js_storekit_start_listener()

For the 6-symbol smoke test (all params/returns shapes in storekit's manifest):

declare void @js_storekit_start_listener()
declare double @js_storekit_load_products(ptr)
declare double @js_storekit_purchase(ptr)
declare double @js_storekit_restore()
declare double @js_storekit_has_subscription()
declare double @js_storekit_get_jws()

All declares match the calls — types come from the FFI-manifest path in lower_call.rs (which is what ffi_signatures-driven calls were always supposed to use).

Test plan

• cargo test --release -p perry --bin perry → 332 passed, 0 failed
• Reproduce from FFI symbols emitted as undefined values in caller IR (compile fails for any importer) storekit#1 (import { js_storekit_start_listener } from \"@perryts/storekit\"; js_storekit_start_listener();) — compiles and runs (exits 0) instead of failing at link
• Inspect generated IR — every FFI symbol has a matching declare external next to its call
• Smoke against an unscoped non-manifest dep (e.g. perry-searchbird-apple-auth) to confirm no regression on the path that already worked