feat(vnext): complete vNext.1 release gate — default chain admission, idempotent init, user key skeleton

- DEFAULT_CHAIN_ADMISSION.md: reviewed and approved, real artifact refs added
- DEFAULT_DATA_IDEMPOTENT_RELEASE_GATE.md: reviewed and approved
- scripts/setup_default_data.sh: idempotent init with --dry-run/--apply/artifact
- scripts/test/test_default_data.sh: 4 test cases all pass
- scripts/acceptance/verify_user_key_self_service.sh: Phase 0 skeleton
- .gitignore: add generated artifact directories

internal/host/sub2api/capability_inventory_test.go

@@ -0,0 +1,76 @@
+package sub2api
+
+import (
+	"testing"
+
+	"sub2api-cn-relay-manager/internal/probe"
+)
+
+func TestBuildCapabilityInventoryClassifiesSupportedWithAdapter(t *testing.T) {
+	t.Parallel()
+
+	inventory := BuildCapabilityInventory(
+		HostCapabilities{
+			Groups:        true,
+			Channels:      true,
+			Plans:         true,
+			Accounts:      true,
+			AccountTest:   true,
+			AccountModels: true,
+			Subscriptions: true,
+		},
+		&probe.CapabilityProfile{
+			TransportProfile: probe.TransportProfile{
+				SupportsOpenAIModels:          true,
+				SupportsOpenAIChatCompletions: true,
+				SupportsOpenAIResponses:       false,
+				KnownAdvisories:               []string{"responses_unsupported_but_chat_ok"},
+			},
+			ModelProfiles: []probe.ModelCapabilityProfile{{
+				RawModelID:           "kimi-k2.6",
+				CanonicalModelFamily: "kimi-k2.6",
+				SmokeChatOK:          true,
+			}},
+		},
+	)
+
+	if !inventory.HostReady {
+		t.Fatal("HostReady = false, want true")
+	}
+	if len(inventory.Models) != 1 {
+		t.Fatalf("len(Models) = %d, want 1", len(inventory.Models))
+	}
+	if inventory.Models[0].SupportLevel != SupportLevelWithPluginAdapter {
+		t.Fatalf("SupportLevel = %q, want %q", inventory.Models[0].SupportLevel, SupportLevelWithPluginAdapter)
+	}
+}
+
+func TestBuildCapabilityInventoryClassifiesUpstreamUnhealthy(t *testing.T) {
+	t.Parallel()
+
+	inventory := BuildCapabilityInventory(
+		HostCapabilities{Groups: true, Channels: true, Accounts: true, AccountTest: false},
+		&probe.CapabilityProfile{
+			TransportProfile: probe.TransportProfile{
+				SupportsOpenAIModels:          true,
+				SupportsOpenAIChatCompletions: false,
+				SupportsOpenAIResponses:       false,
+			},
+			ModelProfiles: []probe.ModelCapabilityProfile{{
+				RawModelID:           "glm-4.5",
+				CanonicalModelFamily: "glm-4.5",
+				SmokeChatOK:          false,
+			}},
+		},
+	)
+
+	if inventory.HostReady {
+		t.Fatal("HostReady = true, want false when required host capabilities are missing")
+	}
+	if len(inventory.Models) != 1 {
+		t.Fatalf("len(Models) = %d, want 1", len(inventory.Models))
+	}
+	if inventory.Models[0].SupportLevel != SupportLevelUpstreamUnhealthy {
+		t.Fatalf("SupportLevel = %q, want %q", inventory.Models[0].SupportLevel, SupportLevelUpstreamUnhealthy)
+	}
+}