floats iter 1.4: refresh canonical.rs 'no floats' doc comment

crates/ailang-core/src/canonical.rs

@@ -9,9 +9,14 @@
 //! The single entry point is [`to_bytes`]. This module deliberately
 //! does **not** parse, validate, or hash — it only emits bytes. It also
 //! does not attempt to be a general-purpose canonical-JSON library;
-//! number-formatting follows whatever `serde_json::Number::to_string`
-//! does, which is fine for the AILang AST (integers and short strings;
-//! no floats).
+//! Number formatting follows whatever `serde_json::Number::to_string`
+//! does — used only for the AST integer literals. Float literals do
+//! not go through the number path; [`crate::ast::Literal::Float`]
+//! carries its IEEE-754 bit pattern as a `u64` and serialises via a
+//! 16-character lowercase hex *string*, which the canonical writer
+//! treats like any other string. The string path is what makes float
+//! canonical bytes bit-stable across `serde_json` versions and what
+//! lets NaN / ±Inf round-trip at all (they cannot, as JSON numbers).
 //!
 //! # Examples
 //!