feat: per-sink delivery, journal forwarding, and operational API

Persistence:
- one delivery state per sink, with claim, crash recovery, and index replacement
- retention for delivered and dead records
- LMDB writes moved off the event loop

Pipeline:
- one attempt per dispatch, with the next try scheduled by next_retry_at
- backpressure through max_queue_size
- reload re-reads YAML; SIGTERM drains and SIGHUP reloads

Plugins:
- journald source, enricher and filter processors, Loki sink
- built-ins register when entry points are missing

API and CLI:
- health, metrics, per-sink queue, and dead-letter replay
- startup prints the pipeline on one line

Tests:
- dispatch, plugins, metrics, CLI, and persistence coverage

tests/test_metrics.py

@@ -0,0 +1,50 @@
+from __future__ import annotations
+
+import asyncio
+
+import pytest
+
+from daena.api.metrics import MetricsServer, MetricsSnapshot, render_prometheus
+
+
+def test_render_prometheus_includes_sink_state() -> None:
+    text = render_prometheus(
+        MetricsSnapshot(
+            running=True,
+            stored_records=3,
+            oldest_inflight_seconds=12,
+            deliveries={("central", "pending"): 2, ("central", "delivered"): 1},
+            sink_results={"central": {"delivered": 4, "failed": 1, "dead": 0}},
+        )
+    )
+    assert "daena_up 1" in text
+    assert "daena_records 3" in text
+    assert "daena_oldest_inflight_seconds 12" in text
+    assert 'daena_delivery_records{sink="central",state="pending"} 2' in text
+    assert 'daena_sink_deliveries_total{sink="central",result="failed"} 1' in text
+
+
+@pytest.mark.asyncio
+async def test_metrics_server_serves_text() -> None:
+    snapshot = MetricsSnapshot(
+        running=True,
+        stored_records=0,
+        oldest_inflight_seconds=0,
+        deliveries={},
+        sink_results={},
+    )
+    server = MetricsServer("127.0.0.1", 0, lambda: snapshot, lambda: {"status": "ok"})
+    await server.start()
+    assert server._server is not None
+    sockets = server._server.sockets
+    assert sockets is not None
+    port = sockets[0].getsockname()[1]
+    reader, writer = await asyncio.open_connection("127.0.0.1", port)
+    writer.write(b"GET /metrics HTTP/1.1\r\nHost: localhost\r\n\r\n")
+    await writer.drain()
+    data = await reader.read()
+    writer.close()
+    await writer.wait_closed()
+    await server.stop()
+    assert b"200 OK" in data
+    assert b"daena_up 1" in data