fix(mac): add tailnet discovery fallback and debug CLI

apps/macos/Tests/ClawdbotIPCTests/WideAreaGatewayDiscoveryTests.swift

@@ -0,0 +1,49 @@
+import Testing
+@testable import ClawdbotDiscovery
+
+@Suite
+struct WideAreaGatewayDiscoveryTests {
+    @Test func discoversBeaconFromTailnetDnsSdFallback() {
+        let statusJson = """
+        {
+          "Self": { "TailscaleIPs": ["100.69.232.64"] },
+          "Peer": {
+            "peer-1": { "TailscaleIPs": ["100.123.224.76"] }
+          }
+        }
+        """
+
+        let context = WideAreaGatewayDiscovery.DiscoveryContext(
+            tailscaleStatus: { statusJson },
+            dig: { args, _ in
+                let recordType = args.last ?? ""
+                let nameserver = args.first(where: { $0.hasPrefix("@") }) ?? ""
+                if recordType == "PTR" {
+                    if nameserver == "@100.123.224.76" {
+                        return "steipetacstudio-bridge._clawdbot-bridge._tcp.clawdbot.internal.\n"
+                    }
+                    return ""
+                }
+                if recordType == "SRV" {
+                    return "0 0 18790 steipetacstudio.clawdbot.internal."
+                }
+                if recordType == "TXT" {
+                    return "\"displayName=Peter\\226\\128\\153s Mac Studio (Clawdbot)\" \"transport=bridge\" \"bridgePort=18790\" \"gatewayPort=18789\" \"tailnetDns=peters-mac-studio-1.sheep-coho.ts.net\" \"cliPath=/Users/steipete/clawdbot/src/entry.ts\""
+                }
+                return ""
+            })
+
+        let beacons = WideAreaGatewayDiscovery.discover(
+            timeoutSeconds: 2.0,
+            context: context)
+
+        #expect(beacons.count == 1)
+        let beacon = beacons[0]
+        let expectedDisplay = "Peter\u{2019}s Mac Studio (Clawdbot)"
+        #expect(beacon.displayName == expectedDisplay)
+        #expect(beacon.bridgePort == 18790)
+        #expect(beacon.gatewayPort == 18789)
+        #expect(beacon.tailnetDns == "peters-mac-studio-1.sheep-coho.ts.net")
+        #expect(beacon.cliPath == "/Users/steipete/clawdbot/src/entry.ts")
+    }
+}