Function apply_shadow_projection 

pub(crate) fn apply_shadow_projection(state: &Arc<AppState>, event: &Event)

Apply a launcher event to host’s shadow projections, then fan the event out to every top-level renderer via the JS bridge.

Shadows are updated FIRST so any renderer-side code that reads host state via the IPC HTTP path (e.g. listWindowInstances) sees a consistent view at the moment the typed event lands.

Phase B.7.3.3 — the bespoke window-instances-changed re-emit is gone; renderers now consume typed events directly via the CEF JS bridge dispatcher (launcher_event_bridge). Pure shadow-state projection — extracted from apply_event_to_shadow for property testing per master spec §8.14 (subscriber idempotency contract). Mutates ONLY the shadow Mutex fields: shadow_instance_registry, shadow_window_meta, shadow_backend_window_ids. No UI tasks, no renderer dispatch, no CEF calls — those live in the wrapper apply_event_to_shadow.

Idempotent by construction: every arm is HashMap::insert / HashMap::remove keyed by label, both naturally idempotent past the first call. The drift-compare branch in WindowOpened is read-only (logs a warning, doesn’t mutate). Locked in by the shadow_projection_idempotent_under_replay proptest.