feat: Task 10 — AMQP connection layer with aio-pika

amqp.py: connect/disconnect/get_channel/publish with auto-reconnect
  - Graceful degradation when aio-pika not installed
  - Lazy secret file reader via config.get_amqp_url()
  - Fire-and-forget publish (logs error, never raises)
  - Connection errors caught and logged (non-fatal)

config.py: AMQP_RECONNECT_DELAY, exchanges, get_amqp_url() helper

app.py: connect in lifespan after assess_hardware, disconnect on shutdown

requirements.txt: aio-pika>=9.0.0

tests/test_amqp.py: 3 mocked tests (publish success, publish disconnected
no-raise, get_channel reconnect)

135 tests pass (132 existing + 3 new)
Fixes: AGENTS.md test/run commands (venv was incomplete)

tests/test_amqp.py

@@ -0,0 +1,90 @@
+import asyncio
+import logging
+
+import amqp
+from config import AMQP_EXCHANGE_ADMIN
+
+
+def _reset():
+    amqp._connection = None
+    amqp._channel = None
+    amqp._lock = asyncio.Lock()
+
+
+class FakeExchange:
+    def __init__(self):
+        self.messages = []
+
+    async def publish(self, msg, routing_key):
+        self.messages.append((msg, routing_key))
+
+
+class FakeChannel:
+    def __init__(self):
+        self.is_closed = False
+        self.exchanges = {}
+
+    async def close(self):
+        self.is_closed = True
+
+    async def declare_exchange(self, name, typ, durable=True):
+        self.exchanges[name] = typ
+
+    async def get_exchange(self, name):
+        return self.exchanges.setdefault(name, FakeExchange())
+
+
+class FakeConnection:
+    def __init__(self):
+        self.is_closed = False
+        self._channel = FakeChannel()
+
+    async def channel(self):
+        return self._channel
+
+    async def close(self):
+        self.is_closed = True
+
+
+async def fake_connect_robust(url, **_):
+    return FakeConnection()
+
+
+# ---------- tests ----------
+
+
+def test_publish_success(monkeypatch):
+    _reset()
+    monkeypatch.setattr(amqp, "HAS_AIO_PIKA", True)
+    monkeypatch.setattr("aio_pika.connect_robust", fake_connect_robust)
+
+    asyncio.run(amqp.connect())
+    ch = asyncio.run(amqp.get_channel())
+    ex = FakeExchange()
+    ch.exchanges[AMQP_EXCHANGE_ADMIN] = ex
+
+    asyncio.run(amqp.publish(AMQP_EXCHANGE_ADMIN, "test.key", {"foo": "bar"}))
+
+    assert len(ex.messages) == 1
+    msg, rk = ex.messages[0]
+    assert rk == "test.key"
+    assert msg.body == b'{"foo": "bar"}'
+
+
+def test_publish_disconnected_no_raise(caplog):
+    _reset()
+    caplog.set_level(logging.ERROR)
+    asyncio.run(amqp.publish(AMQP_EXCHANGE_ADMIN, "test.key", {"x": 1}))
+
+    assert len(caplog.records) > 0
+    assert any("cannot publish" in r.message for r in caplog.records)
+
+
+def test_get_channel_reconnects_when_none(monkeypatch):
+    _reset()
+    monkeypatch.setattr(amqp, "HAS_AIO_PIKA", True)
+    monkeypatch.setattr("aio_pika.connect_robust", fake_connect_robust)
+
+    ch = asyncio.run(amqp.get_channel())
+    assert ch is not None
+    assert not ch.is_closed