Extend OAuth2 CIMD for compliance portal clients

Teach CIMD registration and discovery about per-portal client
metadata, and carry portal context through token and ID token
issuance for downstream session creation.

Signed-off-by: Bryan Frimin <bryan@probo.com>

pkg/iam/oauth2/cimd_allowance_test.go

@@ -0,0 +1,55 @@
+// Copyright (c) 2026 Probo Inc <hello@probo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package oauth2
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestCIMDAllowance(t *testing.T) {
+	t.Parallel()
+
+	t.Run(
+		"denied is not allowed and does not skip consent",
+		func(t *testing.T) {
+			t.Parallel()
+
+			assert.False(t, CIMDAllowanceDenied.Allowed())
+			assert.False(t, CIMDAllowanceDenied.SkipsConsent())
+		},
+	)
+
+	t.Run(
+		"allowed permits client use but still requires consent",
+		func(t *testing.T) {
+			t.Parallel()
+
+			assert.True(t, CIMDAllowanceAllowed.Allowed())
+			assert.False(t, CIMDAllowanceAllowed.SkipsConsent())
+		},
+	)
+
+	t.Run(
+		"allowed skip consent is the only first-party bypass",
+		func(t *testing.T) {
+			t.Parallel()
+
+			assert.True(t, CIMDAllowanceAllowedSkipConsent.Allowed())
+			assert.True(t, CIMDAllowanceAllowedSkipConsent.SkipsConsent())
+		},
+	)
+}