add is_finished and fix rustflags

[Pistonight]

New rustflags requirement since Oct 2025

[target.wasm32-unknown-unknown]
rustflags = [
    "-C", "target-feature=+atomics",
    "-Clink-args=--shared-memory",
    "-Clink-args=--import-memory",
    "-Clink-args=--max-memory=1073741824",
    "-Clink-args=--export=__wasm_init_tls",
    "-Clink-args=--export=__tls_size",
    "-Clink-args=--export=__tls_align",
    "-Clink-args=--export=__tls_base",
]