Scaffold Phase 0: agent -> Redpanda -> ingest -> ClickHouse -> api -> web

End-to-end log pipeline for Linux hosts, per /docs/architecture.md:

- proto: shared gRPC contract (agent <-> ingest), Go bindings checked in
- agent: Rust, musl-targeted, journald/file sourcing, RFC5424 parser,
  mTLS gRPC client, no required config for the common case
- ingest: Go, single binary with --mode server|consumer|all; gRPC front
  end forwards to Redpanda unchanged, consumer normalizes and
  batch-writes to ClickHouse with at-least-once delivery
- storage: ClickHouse schema + a plain SQL-file migration runner
- api: minimal SELECT-only query endpoint, plain REST (not gRPC+gateway
  yet -- see api/README.md)
- web: SvelteKit static SPA, one query page
- transport: Redpanda compose + topic provisioning
- cli: sentryctl ping stub
- hack/dev-certs: throwaway CA + cert generation for local mTLS
- root docker-compose.yml + docs/phase-0-runbook.md tie it together

Not yet run end-to-end against real Docker/ClickHouse/Redpanda -- see the
runbook's caveats section before relying on this working as-is.

ingest/Dockerfile

@@ -0,0 +1,15 @@
+# Build context must be the repo root (sentry/), not ingest/, since this
+# needs both ingest/ and proto/:
+#   docker build -f ingest/Dockerfile -t sentry-ingest .
+
+FROM golang:1.25-alpine AS builder
+WORKDIR /src
+COPY proto ./proto
+COPY ingest ./ingest
+WORKDIR /src/ingest
+RUN go mod download
+RUN CGO_ENABLED=0 GOOS=linux go build -o /out/ingest ./cmd/ingest
+
+FROM gcr.io/distroless/static-debian12
+COPY --from=builder /out/ingest /ingest
+ENTRYPOINT ["/ingest"]