Interest in no_std + alloc support?

[lilith]

Hi! I'm interested in using quantizr in a no_std environment (embedded/WASM use cases).

I've prepared a PR (#2) that adds no_std + alloc support with minimal changes:

Changes:

• Conditional #![no_std] when std feature is disabled
• Use hashbrown::HashMap in no_std mode (std mode uses std::collections::HashMap)
• Use num-traits with libm for f32 math methods (sqrt, round, powf) in no_std
• Replace std::arch → core::arch, std::fmt → core::fmt, etc.
• Use core::error::Error (stable since Rust 1.81)

Usage:

# Default (std) - no change
quantizr = "1.4.3"

# no_std + alloc
quantizr = { version = "1.4.3", default-features = false }

Dependencies added:

• hashbrown (only used in no_std mode)
• num-traits with libm feature (only used in no_std mode)

All existing tests pass, and the crate builds successfully on thumbv7em-none-eabihf.

Would you be interested in this functionality? Happy to adjust the implementation based on feedback.