Implement ingest-service: MQTT -> ClickHouse (batched) + RabbitMQ event

Subscribes to devices/+/telemetry, validates payloads, buffers writes into
ClickHouse (flush on size or interval), and emits a per-reading event on
RabbitMQ for rule-engine-service to consume later. Adds the initial Postgres
and ClickHouse schema migrations, a Dockerfile, and wires the service into
docker-compose. Verified end-to-end via docker compose + mosquitto_pub: row
lands in ClickHouse and the event reaches the telemetry.new_reading queue.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

services/ingest-service/internal/batch/batcher_test.go

@@ -0,0 +1,84 @@
+package batch
+
+import (
+	"context"
+	"io"
+	"log/slog"
+	"testing"
+	"time"
+
+	"git.cactoz.su/cacto/home_automatization/services/ingest-service/internal/telemetry"
+)
+
+func discardLogger() *slog.Logger {
+	return slog.New(slog.NewTextHandler(io.Discard, nil))
+}
+
+func reading(deviceID string) telemetry.Reading {
+	return telemetry.Reading{DeviceID: deviceID, ZoneID: "z1", SensorType: "temperature", Value: 1}
+}
+
+func awaitBatch(t *testing.T, flushed chan []telemetry.Reading, timeout time.Duration) []telemetry.Reading {
+	t.Helper()
+	select {
+	case batch := <-flushed:
+		return batch
+	case <-time.After(timeout):
+		t.Fatal("timed out waiting for flush")
+		return nil
+	}
+}
+
+func TestBatcher_FlushesOnSize(t *testing.T) {
+	flushed := make(chan []telemetry.Reading, 1)
+	b := New(3, time.Hour, time.Second, func(_ context.Context, r []telemetry.Reading) error {
+		flushed <- r
+		return nil
+	}, discardLogger())
+	b.Start()
+	defer b.Stop()
+
+	b.Add(reading("a"))
+	b.Add(reading("b"))
+	b.Add(reading("c")) // hits maxSize, should trigger an immediate flush
+
+	batch := awaitBatch(t, flushed, time.Second)
+	if len(batch) != 3 {
+		t.Fatalf("got %d readings, want 3", len(batch))
+	}
+}
+
+func TestBatcher_FlushesOnInterval(t *testing.T) {
+	flushed := make(chan []telemetry.Reading, 1)
+	b := New(100, 20*time.Millisecond, time.Second, func(_ context.Context, r []telemetry.Reading) error {
+		flushed <- r
+		return nil
+	}, discardLogger())
+	b.Start()
+	defer b.Stop()
+
+	b.Add(reading("a"))
+
+	batch := awaitBatch(t, flushed, time.Second)
+	if len(batch) != 1 {
+		t.Fatalf("got %d readings, want 1", len(batch))
+	}
+}
+
+func TestBatcher_StopFlushesRemainder(t *testing.T) {
+	flushed := make(chan []telemetry.Reading, 1)
+	b := New(100, time.Hour, time.Second, func(_ context.Context, r []telemetry.Reading) error {
+		flushed <- r
+		return nil
+	}, discardLogger())
+	b.Start()
+
+	b.Add(reading("a"))
+	b.Add(reading("b"))
+	b.Stop()
+
+	batch := awaitBatch(t, flushed, time.Second)
+	if len(batch) != 2 {
+		t.Fatalf("got %d readings, want 2", len(batch))
+	}
+}