feat(host): Keychain and Credential Manager token stores, a macOS/Windows CI job (P11a step 0)

The agent path was Linux-only because tokens had a keyring store only
there (every other OS hit NOT_YET, so `connect` and the bridge failed).
D-56's destination is one installation for macOS, Windows and Linux.
Both new stores sit behind the same Items trait as the Secret Service,
so INVARIANT 4 (one account, one item, locked is an error) is kept once
and tested once through the file keyring. Windows credentials have a
unique target name, so a probe stands in for a search.

New dependencies (ledger-host only, target-gated): apple-native-keyring-store
(feature keychain) and windows-native-keyring-store, the stores the
keyring-core 1 API we already use is published with. No ledger-core change.

The `portable` job builds and tests the workspace on macos-latest and
windows-latest. Windows is allowed to fail: the rest of the host is
Unix-only (inventory in docs/packaging.md). Not verified locally: no
macOS or Windows target is installed; CI is the evidence.

Also pins cargo-packager, cargo-packager-updater and cargo-generate-rpm
in mise.toml for the trial, and records that the trial is not yet run.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

Cargo.lock

@@ -249,6 +249,17 @@ version = "1.0.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "330a5ed07fa54e4702c9d6c4174f74427fc0ef6e214bbd677ae50a5099946470"
 
+[[package]]
+name = "apple-native-keyring-store"
+version = "1.0.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2b350bfd03649e07aa05c0a81b3e15934374e585c98204a57e20b9d49f49bb9a"
+dependencies = [
+ "keyring-core",
+ "log",
+ "security-framework",
+]
+
 [[package]]
 name = "approx"
 version = "0.5.1"
@@ -877,6 +888,12 @@ dependencies = [
  "syn 3.0.7",
 ]
 
+[[package]]
+name = "byteorder"
+version = "1.5.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1fd0f2584146f6f2ef48085050886acf353beff7305ebd1ae69500e27c67f64b"
+
 [[package]]
 name = "byteorder-lite"
 version = "0.1.0"
@@ -3964,6 +3981,7 @@ dependencies = [
 name = "ledger-host"
 version = "0.1.0"
 dependencies = [
+ "apple-native-keyring-store",
  "base64 0.22.1",
  "keyring-core",
  "ledger-core",
@@ -3978,6 +3996,7 @@ dependencies = [
  "tempfile",
  "tokio",
  "tokio-util",
+ "windows-native-keyring-store",
  "zbus-secret-service-keyring-store",
  "zeroize",
 ]
@@ -8723,6 +8742,19 @@ version = "0.2.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "f0805222e57f7521d6a62e36fa9163bc891acd422f971defe97d64e70d0a4fe5"
 
+[[package]]
+name = "windows-native-keyring-store"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "063426e76fdec7438d56bb777f67e318a84a25c707b07e575cb8b78e10c028f8"
+dependencies = [
+ "byteorder",
+ "keyring-core",
+ "regex",
+ "windows-sys 0.61.2",
+ "zeroize",
+]
+
 [[package]]
 name = "windows-numerics"
 version = "0.3.1"