Static SHUTDOWN_REQUESTED 

pub static SHUTDOWN_REQUESTED: AtomicBool

Global shutdown flag, set by the CTRL-C handler.

This uses a raw AtomicBool instead of relying solely on CancellationToken because the indexing pipeline is largely synchronous (ONNX inference, file I/O) and the flag must be visible from any thread without async polling.

Checked between files and between embedding mini-batches so that CTRL-C is honoured within a few seconds even during heavy CPU work.