Add Dockerfile and move ingest service

Containerize the telemetry ingest service and reorganize source layout. Added misc/data/Dockerfile with a multi-stage build (golang:1.23-alpine -> alpine:3.23) to produce /app/telemetry-ingest, run as a non-root user, expose :8080, and provide default env vars for configuration (LISTEN_ADDR, MAX_BODY_BYTES, RATE_LIMIT_RPM, RATE_BURST, RATE_KEY_MODE, ENABLE_REQUEST_LOGGING, UPSTREAM_TIMEOUT_MS). Renamed misc/ingest.go to misc/data/service.go to reflect the new directory structure.

misc/data/Dockerfile

@@ -0,0 +1,21 @@
+# build stage
+FROM golang:1.23-alpine AS build
+WORKDIR /src
+COPY . .
+RUN go build -trimpath -ldflags "-s -w" -o /out/telemetry-ingest ./main.go
+
+# runtime stage
+FROM alpine:3.23
+RUN adduser -D -H -s /sbin/nologin app
+USER app
+WORKDIR /app
+COPY --from=build /out/telemetry-ingest /app/telemetry-ingest
+EXPOSE 8080
+ENV LISTEN_ADDR=":8080" \
+    MAX_BODY_BYTES="1024" \
+    RATE_LIMIT_RPM="60" \
+    RATE_BURST="20" \
+    RATE_KEY_MODE="ip" \
+    ENABLE_REQUEST_LOGGING="false" \
+    UPSTREAM_TIMEOUT_MS="4000"
+CMD ["/app/telemetry-ingest"]