kornia-rs coding style

Run cargo fmt and clippy (-D warnings) before every commit.

Naming

• Functions/variables snake_case, types PascalCase.
• Conversions are <output>_from_<input>: gray_from_rgb, rgb_from_gray, bgr_from_rgb. Never rgb_to_gray / gray_to_rgb.
• Metadata APIs use *_layout (e.g. ImageLayout), not *_info.
• Domain-specific names (image_src, homography_dst), not data, helper.

Errors

• Library crates use thiserror error enums (e.g. ImageError); no anyhow.
• No unwrap(), expect(), panic!() in library code; propagate with ?. Constructors that can fail return Result.
• Variants carry context (SizeMismatch { expected, got }), never Generic("failed").
• Tests may unwrap, but prefer -> Result<(), Box<dyn Error>> with ?.

Documentation

Every pub item has ///; every crate has //!. Public functions require # Arguments, # Returns, # Errors sections, plus a compilable # Example for non-trivial APIs (runs as a doctest: cargo test --doc -p <crate>). Comments state invariants/rationale only — no obvious comments, no AI/prompt commentary, English only.

Safety

Avoid unsafe. Every unsafe block is preceded by // SAFETY: explaining why it is sound. Prefer bytemuck/zerocopy over raw pointers. No transmute/const-casting without a soundness argument.

Other conventions

• Replace numeric literals used as thresholds, borders or loop bounds with named consts.
• Return domain structs, not tuples of loosely related Vecs; use Option for empty results.
• Borrow instead of .clone(); never clone images/tensors needlessly.
• Pre-allocated &mut outputs, no allocation in hot paths, iterators over index loops, match on enums rather than strings.
• Tests live in #[cfg(test)] modules, deterministic and focused.
• Reuse existing kornia-rs utilities instead of reimplementing them (procedure: kornia-code-review section 0b).
• New dependencies: minimal, mind build time and binary size.