Profiles v2: chipset+variant top-level keys, minimal per-drive data

profiles.json: { "mt1959_a": [...], "mt1959_b": [...], "renesas": [] }
Each profile: identity + signature + firmware (3 fields)
Platform enum replaces Chipset — section determines variant

src/lib.rs

@@ -85,7 +85,7 @@ pub mod keydb;
 pub use error::{Error, Result};
 pub use drive::{DriveSession, find_drive, find_drives, resolve_device};
 pub use identity::DriveId;
-pub use profile::{DriveProfile, Chipset};
+pub use profile::DriveProfile;
 // Platform trait is pub(crate) — callers use DriveSession, not Platform directly
 pub use scsi::ScsiTransport;
 pub use speed::DriveSpeed;