fix(secrets): enable the real keyring backends on macOS and Windows

keyring 3.x ships no `default` feature contents, and every platform arm
reads `not(feature = "...-native")` -> `pub use mock as default`. Naming
no features therefore selected the in-memory mock on macOS and Windows,
whose writes succeed and whose master key dies with the process, while
`Backend::new` still reported `BackendKind::Keyring`.

The consequence is that every offline track's content key becomes
undecryptable on the next launch, so playback treats it as a cache miss
and silently re-streams what the user had already downloaded.

Linux is left off the list because qbz-credentials already enables
`async-secret-service` and Cargo unifies features; naming
`sync-secret-service` here would trip keyring's own compile_error for
enabling both halves of a store.

Proven with a probe wrapping in one process and unwrapping in another,
on the same machine, changing only this line:
  before: backend = Keyring, UNWRAP FAILED: cipher error: aead::Error
  after:  backend = Keyring, UNWRAPPED OK

crates/Cargo.lock

@@ -3931,9 +3931,13 @@ version = "3.6.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "eebcc3aff044e5944a8fbaf69eb277d11986064cba30c468730e8b9909fb551c"
 dependencies = [
+ "byteorder",
  "dbus-secret-service",
  "log",
  "secret-service",
+ "security-framework 2.11.1",
+ "security-framework 3.7.0",
+ "windows-sys 0.60.2",
  "zbus 4.4.0",
  "zeroize",
 ]
@@ -7292,7 +7296,7 @@ dependencies = [
  "openssl-probe",
  "rustls-pki-types",
  "schannel",
- "security-framework",
+ "security-framework 3.7.0",
 ]
 
 [[package]]
@@ -7415,6 +7419,19 @@ dependencies = [
  "zbus 4.4.0",
 ]
 
+[[package]]
+name = "security-framework"
+version = "2.11.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "897b2245f0b511c87893af39b033e5ca9cce68824c4d7e7630b5a1d339658d02"
+dependencies = [
+ "bitflags 2.13.0",
+ "core-foundation 0.9.4",
+ "core-foundation-sys",
+ "libc",
+ "security-framework-sys",
+]
+
 [[package]]
 name = "security-framework"
 version = "3.7.0"