collapse freemkv-unlock into one crate; ld becomes a module

Replace the ld/aacs/css member-crate workspace with a single freemkv-unlock
crate: the generic Unlocker contract + SCSI transport contract at the crate
root (lib.rs, scsi.rs, error.rs), and the firmware unlocker as the self-
contained src/ld module. The contract is repo-agnostic raw types (DriveId,
HostCert, DiscKind, Unlocked, UnlockError) with NO libfreemkv dependency, so
libfreemkv will depend on this crate (one-way, no cycle) and dispatch via
all_unlockers(). ld now impl crate::Unlocker, takes its own DriveId (4 raw
fields, no INQUIRY parsing), and returns a raw Option<[u8;16]> VID. The old
aacs/css plugin wrappers are removed; their crypto moves in from libfreemkv in
the next stages. 31 tests pass.

Cargo.toml

@@ -1,15 +1,14 @@
-# freemkv-unlock — unlocker plugins for libfreemkv.
-#
-# libfreemkv ships only the `Unlocker` trait + registry and stays firmware-clean.
-# Each member here is one concrete unlocker, registered into libfreemkv by a
-# single `register_unlocker(...)` line in the consuming binary — so dropping an
-# unlocker is deleting that one line plus the dependency (delete-to-comply).
-#
-# Members:
-#   ld   — LibreDrive (MediaTek MT1959 firmware unlock)
-#   aacs — AACS host-certificate bus-auth unlock (Blu-ray / UHD)
-#   css  — CSS (DVD-Video) bus-auth unlock
-#   (future unlockers go here as additional members)
-[workspace]
-resolver = "2"
-members = ["ld", "aacs", "css"]
+[package]
+name = "freemkv-unlock"
+version = "1.2.0"
+edition = "2024"
+rust-version = "1.86"
+license = "AGPL-3.0-only"
+description = "Unlock layer for the freemkv toolchain: the Unlocker contract + self-contained firmware/AACS/CSS unlocker modules. libfreemkv depends on this and dispatches via all_unlockers()."
+repository = "https://github.com/freemkv/freemkv-unlock"
+
+[dependencies]
+serde = { version = "1", features = ["derive"] }
+serde_json = "1"
+base64 = "0.22.1"
+tracing = "0.1"