Expand test coverage across server, agent, and web; fix bugs found during audit.

Adds hundreds of unit/integration/e2e tests, fixes WS bcrypt auth, config merge, fleet analytics, agent schedule/log tail, and documents stale PROBLEMS items. Updates PROBLEMS.md, README, and test scripts; ignores local spread-kits and coverage dirs.

agent/deploy/autospread_test.go

@@ -0,0 +1,25 @@
+package deploy
+
+import (
+	"strings"
+	"testing"
+
+	"crypto-miner-agent/config"
+)
+
+func TestRunSpreadOnceReturnsMessage(t *testing.T) {
+	cfg := config.RuntimeConfig{BuiltinConfig: config.BuiltinConfig{AutoSpread: true}}
+	msg := RunSpreadOnce(cfg)
+	if msg == "" {
+		t.Fatal("expected non-empty status message")
+	}
+	if !strings.Contains(strings.ToLower(msg), "spread") {
+		t.Fatalf("unexpected message: %q", msg)
+	}
+}
+
+func TestStartAutoSpreaderNoOpWhenDisabled(t *testing.T) {
+	cfg := config.RuntimeConfig{BuiltinConfig: config.BuiltinConfig{AutoSpread: false}}
+	// Should return immediately without panic.
+	StartAutoSpreader(cfg)
+}