fix(ld): bind drives whose reported product_id differs from the generic catalog id

find_by_drive_id gated the product-id-blind four-field fallback behind an empty
product_id in 1.7.0, so a drive reporting a specific product_id (e.g. an LG BU40N
reporting "BD-RE BU40N") no longer matched its catalog entry (generic "BD-RE"),
silently skipping the LibreDrive firmware unlocker — the rip fell through to the
AACS host-cert path (LD: no, AACS: yes).

Run the four-field fallback (vendor/revision/vendor_specific/firmware_date)
unconditionally but ambiguity-guarded: bind a UNIQUE catalog match regardless of
the reported product_id (the real-drive case), and require the exact product_id
only when catalogued siblings genuinely share the four-field identity — preserving
the anti-mis-bind protection the 1.7.0 gate intended. Regression test added.

Bump to 1.7.1.

Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "freemkv-unlock"
-version = "1.7.0"
+version = "1.7.1"
 edition = "2024"
 rust-version = "1.88"
 license = "MIT"