feat!: hide Coder Tasks behind the enable-ai-tasks flag (#28008)

coderd/coderdtest/coderdtest.go

@@ -1866,6 +1866,10 @@ func DeploymentValues(t testing.TB, mut ...func(*codersdk.DeploymentValues)) *co
 	opts := cfg.Options()
 	err := opts.SetDefaults()
 	require.NoError(t, err)
+	// Tasks ship disabled. Tests exercise the enabled behavior by default so
+	// the Tasks suite keeps running; tests for the disabled path opt out
+	// explicitly via the mutators.
+	cfg.EnableAITasks = true
 	for _, fn := range mut {
 		fn(cfg)
 	}