Make an unlocker's ID the name of its directory (closes #98)

Keychain and Secure Enclave unlocker IDs were the creation time to the
minute plus the host name, and passphrase unlocker IDs the time to the
minute, so two created within one minute shared an ID, and `unlocker
select`, `unlocker remove` and the selection after `unlocker add` acted on
the older one. Every unlocker's ID is now its directory name, unique in
its vault. PGP unlocker IDs were `pgp-<fingerprint>`; the check that
refuses a second PGP unlocker for one key now compares the fingerprint in
the other unlockers' metadata.

Model: opus-5-5

internal/cli/unlockers_list_test.go

@@ -48,13 +48,12 @@ const (
 	// listTestVaultName is the name of that synthetic vault.
 	listTestVaultName = "default"
 
-	// listTestGPGKeyID is the GPG key ID recorded in the readable PGP
-	// unlocker's metadata. The unlocker's real ID is derived from it, and
-	// differs from the timestamp-derived fallback ID.
+	// listTestGPGKeyID is the GPG key ID recorded, with a letter appended,
+	// in the PGP unlockers' metadata.
 	listTestGPGKeyID = "DEADBEEFDEADBEEF"
 
 	// listTestUnlockerDirOne and listTestUnlockerDirTwo are the unlocker
-	// directory names under unlockers.d.
+	// directory names under unlockers.d, and so the unlockers' IDs.
 	listTestUnlockerDirOne = "host-pgp-2026-08-09"
 	listTestUnlockerDirTwo = "host-pgp-2026-08-10"
 
@@ -142,8 +141,8 @@ func (f *metadataStatFailFs) Stat(name string) (os.FileInfo, error) {
 	return f.Fs.Stat(name)
 }
 
-// writePGPUnlocker writes a PGP unlocker directory with metadata that
-// yields the real ID "pgp-<keyID>".
+// writePGPUnlocker writes a PGP unlocker directory named dirName, with
+// metadata recording the GPG key ID keyID.
 func writePGPUnlocker(
 	t *testing.T, fs afero.Fs, unlockersDir, dirName string,
 	createdAt time.Time, keyID string,
@@ -256,7 +255,7 @@ func TestUnlockersListSkipsOnlyUnreadableEntries(t *testing.T) {
 
 	require.Len(t, unlockers, 1,
 		"only the entry whose directory was readable may be listed")
-	assert.Equal(t, "pgp-"+listTestGPGKeyID+"A", unlockers[0].ID,
+	assert.Equal(t, listTestUnlockerDirOne, unlockers[0].ID,
 		"the surviving row must carry the real unlocker ID")
 	assert.True(t, unlockers[0].IsCurrent,
 		"the current-unlocker marker must survive the skip")
@@ -272,20 +271,21 @@ func TestUnlockersListReadableEntriesAreListed(t *testing.T) {
 	unlockers := listUnlockersJSON(t, base)
 
 	require.Len(t, unlockers, 2)
-	assert.Equal(t, "pgp-"+listTestGPGKeyID+"A", unlockers[0].ID)
-	assert.Equal(t, "pgp-"+listTestGPGKeyID+"B", unlockers[1].ID)
+	assert.Equal(t, listTestUnlockerDirOne, unlockers[0].ID)
+	assert.Equal(t, listTestUnlockerDirTwo, unlockers[1].ID)
 	assert.True(t, unlockers[0].IsCurrent)
 	assert.False(t, unlockers[1].IsCurrent)
 }
 
 // TestUnlockersListToleratesCorruptMetadata asserts that one unlocker with
 // corrupt metadata does not stop the listing. Metadata that is not JSON
-// leaves that unlocker out; PGP metadata without a usable GPG key ID lists
-// it as "pgp-unknown". The healthy unlocker is listed with its real ID.
+// leaves that unlocker out; PGP metadata without a usable GPG key ID is
+// still listed, under its directory name like any other. The healthy
+// unlocker is listed with its real ID.
 func TestUnlockersListToleratesCorruptMetadata(t *testing.T) {
 	t.Parallel()
 
-	healthyID := "pgp-" + listTestGPGKeyID + "A"
+	healthyID := listTestUnlockerDirOne
 
 	tests := []struct {
 		name     string
@@ -300,12 +300,12 @@ func TestUnlockersListToleratesCorruptMetadata(t *testing.T) {
 		{
 			name:     "GPG key ID of the wrong type",
 			metadata: `{"type": "pgp", "gpgKeyId": 42}`,
-			wantIDs:  []string{healthyID, "pgp-unknown"},
+			wantIDs:  []string{healthyID, listTestUnlockerDirTwo},
 		},
 		{
 			name:     "GPG key ID missing",
 			metadata: `{"type": "pgp"}`,
-			wantIDs:  []string{healthyID, "pgp-unknown"},
+			wantIDs:  []string{healthyID, listTestUnlockerDirTwo},
 		},
 	}
 
@@ -371,7 +371,7 @@ func TestUnlockersListSkipsUnreadableMetadata(t *testing.T) {
 
 			require.Len(t, unlockers, 1,
 				"only the unlocker with usable metadata may be listed")
-			assert.Equal(t, "pgp-"+listTestGPGKeyID+"B", unlockers[0].ID,
+			assert.Equal(t, listTestUnlockerDirTwo, unlockers[0].ID,
 				"the listed row must carry the real unlocker ID")
 		})
 	}