test: assert full key bytes; correct keydb-format docs

Several tests asserted only key[0] (the first byte), which a byte-transposition bug could pass — assert the full 16-byte key everywhere, including a KAT that recomputes the expected VUK-derived keys directly. test_parse_disc_entry used identical all-zero placeholders for M/I/V/U, which couldn't catch a field mix-up; give each field a distinct byte pattern and assert every field.

Docs: keydb-format.md claimed DiscEntry::title was genuinely unused dead code, but it's read by to_keydb_cfg and the redacting Debug impl — correct the comment to only list empty/find_vuk as truly unused. Also cross-reference the two independent MAX_KEYDB_BYTES constants (keydb.rs's decompression cap and keydb_format.rs's on-disk load cap) so they're kept in sync, and bump Cargo.lock's version metadata.

Cargo.lock

@@ -306,7 +306,7 @@ dependencies = [
 
 [[package]]
 name = "freemkv-keysources"
-version = "1.6.14"
+version = "1.7.0"
 dependencies = [
  "base64",
  "flate2",
@@ -319,7 +319,7 @@ dependencies = [
 
 [[package]]
 name = "freemkv-unlock"
-version = "1.6.14"
+version = "1.7.0"
 dependencies = [
  "aes",
  "base64",
@@ -534,7 +534,7 @@ checksum = "3eaf3ede3fee6db1a4c2ee091bf8a8b4dccdc6d17f656fb07896ee72867612f2"
 
 [[package]]
 name = "libfreemkv"
-version = "1.6.14"
+version = "1.7.0"
 dependencies = [
  "aes",
  "base64",
@@ -1271,8 +1271,8 @@ dependencies = [
 
 [[patch.unused]]
 name = "freemkv-engine"
-version = "1.6.14"
+version = "1.7.0"
 
 [[patch.unused]]
 name = "freemkv-i18n"
-version = "1.6.14"
+version = "1.7.0"