lib: remove standalone sector-health verify feature

Delete src/verify.rs (standalone 'read every sector, classify health'
module) + its lib.rs pub mod/pub use. It was old, unused code. The
decrypt-verify gate (disc::verify / UnitVerifier) is a DIFFERENT module and
stays. Relocated the pure chapter_at_offset helper (used by locate_ranges +
autorip's done-card) into disc/mod.rs as a pub fn.

src/lib.rs

@@ -128,10 +128,6 @@ pub mod sector;
 pub(crate) mod speed;
 pub(crate) mod udf;
 pub(crate) mod unlock_bridge;
-pub mod verify;
-
-// Re-export verify types at the crate root for ergonomic imports.
-pub use verify::{SectorRange, SectorStatus, VerifyResult, verify_title};
 
 // ─── Drive lifecycle ────────────────────────────────────────────────────────
 //