all: add ts_omit_serve, start making tailscale serve/funnel be modular

tailscaled tailscale combined (linux/amd64)
     29853147  17384418  31412596 omitting everything
    +  621570 +  219277 +  554256 .. add serve

Updates #17128

Change-Id: I87c2c6c3d3fc2dc026c3de8ef7000a813b41d31c
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>

ipn/ipnlocal/serve_disabled.go

@@ -0,0 +1,34 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build ts_omit_serve
+
+// These are temporary (2025-09-13) stubs for when tailscaled is built with the
+// ts_omit_serve build tag, disabling serve.
+//
+// TODO: move serve to a separate package, out of ipnlocal, and delete this
+// file. One step at a time.
+
+package ipnlocal
+
+import (
+	"tailscale.com/ipn"
+	"tailscale.com/tailcfg"
+)
+
+const serveEnabled = false
+
+type localListener = struct{}
+
+func (b *LocalBackend) DeleteForegroundSession(sessionID string) error {
+	return nil
+}
+
+type funnelFlow = struct{}
+
+func (*LocalBackend) hasIngressEnabledLocked() bool         { return false }
+func (*LocalBackend) shouldWireInactiveIngressLocked() bool { return false }
+
+func (b *LocalBackend) vipServicesFromPrefsLocked(prefs ipn.PrefsView) []*tailcfg.VIPService {
+	return nil
+}