Redundant AtomicCell Error Signaling

[d3v-null]

Several modules in the codebase use an AtomicCell<bool> as an error flag to signal errors between threads (e.g., let error = AtomicCell::new(false);). Each thread sets error.store(true) on error, and other threads check if error.load() to decide whether to exit early. This pattern is used in addition to channels for inter-thread communication.

• src/params/peel/mod.rs
• src/params/vis_convert.rs
• src/params/vis_subtract.rs
• src/params/di_calibration.rs
• src/params/vis_simulate.rs
• src/cli/vis_utils/simulate/mod.rs

In all these cases, threads are already communicating via channels. If a thread encounters an error and exits, it will close its end of the channel, and other threads will receive a SendError or RecvError and can exit cleanly.
The explicit AtomicCell is redundant and adds unnecessary complexity. Relying on channel closure is more idiomatic and robust in Rust.