Resolve review #003 nits N1, N3, N4

- N1: number_from_f64 now returns AlkTypeError::Access for non-finite
  floats instead of silently materializing Value::Null. A NaN/Inf in the
  buffer surfaces as a clear access error rather than a misleading
  'expected a number' validation error.
- N3: drop the dead Value::String arm from check_bytes; the materializer
  only ever emits bytes as an array of u8. Update the validation-model
  docs to match.
- N4: fix stale ADR references in doc comments (ADR-096 -> ADR-002,
  ADR-097 -> ADR-003, ADR-098 -> ADR-004, ADR-101 -> ADR-007).

N2 (BastType::alk_kind returning Struct for ) left as documented;
every current caller resolves the ref first, so forcing Option through
the call sites is churn without benefit.

Verification: cargo test --release (411 pass), cargo clippy --all-targets
-- -D warnings (clean), cargo doc --no-deps (clean).

src/offset_map.rs

@@ -1,4 +1,4 @@
-//! Aligned static `OffsetMap` — Mode 2 of the two layout modes (ADR-096).
+//! Aligned static `OffsetMap` — Mode 2 of the two layout modes (ADR-002).
 //!
 //! Fields have fixed positions with natural alignment padding.
 //! Variable-length fields get a 4-byte length prefix at a known offset;