feat(tests): add live subprocess integration test suite for services

Spins up each service's server.py in a real subprocess via a free ephemeral
port (PORT env var), connects with real protocol clients, and asserts both
correct protocol behavior and RFC 5424 log output.

- 44 live tests across 10 services: http, ftp, smtp, redis, mqtt,
  mysql, postgres, mongodb, pop3, imap
- Shared conftest.py: _ServiceProcess (bg reader thread + queue),
  free_port, live_service fixture, assert_rfc5424 helper
- PORT env var added to all 10 targeted server.py templates
- New pytest marker `live`; excluded from default addopts run
- requirements-live-tests.txt: flask, twisted + protocol clients

tests/live/test_redis_live.py

@@ -0,0 +1,44 @@
+import pytest
+import redis
+
+from tests.live.conftest import assert_rfc5424
+
+
+@pytest.mark.live
+class TestRedisLive:
+    def test_ping_responds(self, live_service):
+        port, drain = live_service("redis")
+        r = redis.Redis(host="127.0.0.1", port=port, socket_timeout=5)
+        assert r.ping() is True
+
+    def test_connect_logged(self, live_service):
+        port, drain = live_service("redis")
+        r = redis.Redis(host="127.0.0.1", port=port, socket_timeout=5)
+        r.ping()
+        lines = drain()
+        assert_rfc5424(lines, service="redis", event_type="connect")
+
+    def test_auth_logged(self, live_service):
+        port, drain = live_service("redis")
+        r = redis.Redis(
+            host="127.0.0.1", port=port, password="wrongpassword", socket_timeout=5
+        )
+        try:
+            r.ping()
+        except Exception:
+            pass
+        lines = drain()
+        assert_rfc5424(lines, service="redis", event_type="auth")
+
+    def test_command_logged(self, live_service):
+        port, drain = live_service("redis")
+        r = redis.Redis(host="127.0.0.1", port=port, socket_timeout=5)
+        r.execute_command("KEYS", "*")
+        lines = drain()
+        assert_rfc5424(lines, service="redis", event_type="command")
+
+    def test_keys_returns_bait_data(self, live_service):
+        port, drain = live_service("redis")
+        r = redis.Redis(host="127.0.0.1", port=port, socket_timeout=5)
+        keys = r.keys("*")
+        assert len(keys) > 0, "Expected bait keys in fake store"