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/internal/config/config_test.go

@@ -0,0 +1,49 @@
+package config
+
+import "testing"
+
+func TestLoadDefaults(t *testing.T) {
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+	if cfg.GRPC.ListenAddr != ":4317" {
+		t.Errorf("GRPC.ListenAddr = %q, want :4317", cfg.GRPC.ListenAddr)
+	}
+	if cfg.Redpanda.Topic != "sentry.logs.raw" {
+		t.Errorf("Redpanda.Topic = %q, want sentry.logs.raw", cfg.Redpanda.Topic)
+	}
+	if cfg.Batch.MaxSize != 500 {
+		t.Errorf("Batch.MaxSize = %d, want 500", cfg.Batch.MaxSize)
+	}
+	if cfg.Batch.FlushIntervalMS != 2000 {
+		t.Errorf("Batch.FlushIntervalMS = %d, want 2000", cfg.Batch.FlushIntervalMS)
+	}
+}
+
+func TestLoadOverridesFromEnv(t *testing.T) {
+	t.Setenv("GRPC_LISTEN_ADDR", ":9999")
+	t.Setenv("REDPANDA_BROKERS", "a:9092,b:9092")
+	t.Setenv("CONSUMER_BATCH_MAX_SIZE", "10")
+
+	cfg, err := Load()
+	if err != nil {
+		t.Fatalf("Load() error = %v", err)
+	}
+	if cfg.GRPC.ListenAddr != ":9999" {
+		t.Errorf("GRPC.ListenAddr = %q, want :9999", cfg.GRPC.ListenAddr)
+	}
+	if len(cfg.Redpanda.Brokers) != 2 || cfg.Redpanda.Brokers[0] != "a:9092" || cfg.Redpanda.Brokers[1] != "b:9092" {
+		t.Errorf("Redpanda.Brokers = %+v, want [a:9092 b:9092]", cfg.Redpanda.Brokers)
+	}
+	if cfg.Batch.MaxSize != 10 {
+		t.Errorf("Batch.MaxSize = %d, want 10", cfg.Batch.MaxSize)
+	}
+}
+
+func TestLoadInvalidBatchSizeErrors(t *testing.T) {
+	t.Setenv("CONSUMER_BATCH_MAX_SIZE", "not-a-number")
+	if _, err := Load(); err == nil {
+		t.Fatal("expected error for non-numeric CONSUMER_BATCH_MAX_SIZE, got nil")
+	}
+}