Replaces the busy-wait polling loop in `waitForWasm` with a `borgstmf:ready` event listener.
This eliminates unnecessary CPU usage during initialization and potentially improves latency.
Also updates the `stmf.wasm` binary to ensure it contains the event dispatch logic present in `pkg/wasm/stmf/main.go`.
Fixes a CI build failure by changing `pkg/player/assets.go` to use directory embedding (`//go:embed frontend`) instead of explicit file embedding, which avoids errors when ignored files (like `demo-track.smsg`) are missing in the CI environment.
5fcb3a2706