perry/system + perry/updater FFI symbols undefined on --target harmonyos (same shape as #395)

[proggeramlug]

Summary

Companion to #395 (which fixed perry_ui_*). The same root cause leaks two more symbol families into the harmonyos libentry.so:

• perry_system_* — 22 symbols (e.g. perry_system_is_dark_mode, perry_system_get_device_model, perry_system_audio_*, perry_system_keychain_*, perry_system_notification_*, perry_get_device_idiom)
• perry_updater_* — 14 symbols

These are defined ONLY in the per-platform UI crates (perry-ui-macos / perry-ui-android / perry-ui-ios / perry-ui-gtk4 / perry-ui-windows), not in perry-runtime or perry-stdlib. On harmonyos there's no perry-ui-harmonyos crate, and unlike perry/ui's App({body: ...}) literal, perry/system + perry/updater calls don't go through the perry-codegen-arkts harvest pass — the LLVM codegen always emits the extern declarations.

So the moment a harmonyos app calls isDarkMode() / getDeviceModel() / keychainSave() / any other perry/system or perry/updater API (from anywhere — top-level, event handler, library code), the OHOS dynamic loader will reject the bundle with Error relocating ... perry_system_X: symbol not found or perry_updater_X: symbol not found.

This will surface immediately on Mango once #395 unblocks embedNSView, because Mango uses perry/system darkmode + locale APIs.

Suggested fix

Extend the perry-runtime/build.rs from #395 to also scan PERRY_SYSTEM_TABLE + PERRY_UPDATER_TABLE from perry-dispatch. Mechanical ~10 LOC change — replace the tables slice with all four tables and adjust the symbol-prefix filter. Each stub is auto-generated as a no-op via the existing ReturnKind → default-value mapping. Same cfg(feature = "ohos-napi") gating; same drift-proof source-of-truth approach.

Optionally, gate per-symbol so calls that DO have a real harmonyos impl (e.g. perry_system_is_dark_mode could route to @ohos.application.Configuration.colorMode via NAPI) get a real implementation instead of the no-op default — but that's per-symbol work and the immediate priority is just getting the link to resolve.

Affected versions

Latent on every Perry version that supports --target harmonyos (#399 onward, v0.5.418+). Masked because #395's perry_ui_embed_nsview fired first; will be the next undefined symbol once #395 lands.

Blocking

Likely the next undefined-symbol blocker after #395 lands. Should be fixed as a same-PR follow-up or immediately after.