integration: replace ad-hoc test timeouts with named constants

Categorised timeouts in integrationutil/timeouts.go remove the drift
opportunity between same-purpose budgets repeated across the suite.
The auth, cli, dns, derp, ssh, and tags tests are swept; acl, route,
and general tests follow in later commits alongside their other
ergonomic fixes.

integration/integrationutil/timeouts.go

@@ -0,0 +1,40 @@
+package integrationutil
+
+import "time"
+
+// CI-scaled convergence budgets. ScaledTimeout doubles each on CI.
+var (
+	// HAConvergeTimeout: routes / ACL / policy propagation to reach
+	// every node and show up in status, traceroute, or curl.
+	HAConvergeTimeout = ScaledTimeout(60 * time.Second)
+
+	// HASlowConvergeTimeout: multi-step failover sequences that need
+	// at least one HA prober cycle plus a data-plane settle.
+	HASlowConvergeTimeout = ScaledTimeout(120 * time.Second)
+
+	// PolicyPropagationTimeout: post-SetPolicy filter rules and peer
+	// reachability to reflect the change. Sized for wgengine's
+	// rule-reload lag on contended CI runners (~2 min observed).
+	PolicyPropagationTimeout = ScaledTimeout(180 * time.Second)
+
+	// AuthFlowTimeout: OIDC / web-auth / preauth-key flows to reach
+	// Running.
+	AuthFlowTimeout = ScaledTimeout(30 * time.Second)
+
+	// StatusReadyTimeout: post-event read to reflect the event
+	// (created node visible in list, set tags visible on node).
+	StatusReadyTimeout = ScaledTimeout(30 * time.Second)
+)
+
+// Polling intervals for EventuallyWithT.
+const (
+	// FastPoll: in-process reads (HA state, route table snapshots).
+	FastPoll = 200 * time.Millisecond
+
+	// SlowPoll: cross-container reads (tailscale status, curl,
+	// headscale API) where each tick pays a docker exec round-trip.
+	SlowPoll = 500 * time.Millisecond
+
+	// PingPoll: gap between full ping-matrix sweeps.
+	PingPoll = 2 * time.Second
+)