[management] Rework Agent Network endpoint identity and settings bootstrap (#7085)

Store the per-account gateway endpoint as {domain, proxy_address} with a
global unique index on the full hostname; dedicated = (domain ==
proxy_address). Bootstrap becomes an explicit POST carrying exactly one
of proxy_address (server allocates an adjective-noun label beneath it)
or endpoint (claimed verbatim, address-first); provider create loses its
bootstrap side effect. PUT is a full replace with every field required —
the immutable identity fields must be echoed unchanged and a mismatch is
rejected with 422. A guarded DELETE releases the endpoint: refused with
412 while providers exist or a proxy is actively serving the endpoint
hostname (matched case-insensitively); re-creating bootstraps fresh. A
self-addressed pin excludes its address from the account's cluster allow
list, and the live mapping update path now addresses the serving proxy
from the synthesized service. Existing rows are migrated on all three
store engines.

management/server/agentnetwork_realstack_test.go

@@ -92,6 +92,14 @@ func TestAgentNetwork_ProviderCRUD_FansOutToProxyAndClientPeers(t *testing.T) {
 	// UpdateAccountPeers, which is the path under test.
 	agentMgr := agentnetwork.NewManager(am.Store, permissions.NewManager(am.Store), am, nil)
 
+	_, err = agentMgr.CreateSettings(ctx, adminUserID, agenttypes.DefaultSettings(accountID), clusterAddr, "")
+	require.NoError(t, err, "CreateSettings must bootstrap the endpoint")
+	// The bootstrap itself reconciles and queues updates on both channels;
+	// drain them so the fan-out assertions below can only be satisfied by the
+	// operation under test, not by this leftover.
+	drain(clientCh)
+	drain(proxyCh)
+
 	provider, err := agentMgr.CreateProvider(ctx, adminUserID, &agenttypes.Provider{
 		AccountID:   accountID,
 		ProviderID:  "openai_api",
@@ -100,7 +108,7 @@ func TestAgentNetwork_ProviderCRUD_FansOutToProxyAndClientPeers(t *testing.T) {
 		APIKey:      "sk-test-key",
 		Enabled:     true,
 		Models:      []agenttypes.ProviderModel{{ID: "gpt-5.4"}},
-	}, clusterAddr)
+	})
 	require.NoError(t, err, "CreateProvider must succeed")
 
 	policy, err := agentMgr.CreatePolicy(ctx, adminUserID, &agenttypes.Policy{