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_postgres_live.py

@@ -0,0 +1,75 @@
+import pytest
+
+from tests.live.conftest import assert_rfc5424
+
+
+@pytest.mark.live
+class TestPostgresLive:
+    def test_handshake_received(self, live_service):
+        port, drain = live_service("postgres")
+        import psycopg2
+        try:
+            psycopg2.connect(
+                host="127.0.0.1",
+                port=port,
+                user="admin",
+                password="password",
+                dbname="production",
+                connect_timeout=5,
+            )
+        except psycopg2.OperationalError:
+            pass  # expected: honeypot rejects auth
+
+    def test_startup_logged(self, live_service):
+        port, drain = live_service("postgres")
+        import psycopg2
+        try:
+            psycopg2.connect(
+                host="127.0.0.1",
+                port=port,
+                user="postgres",
+                password="secret",
+                dbname="postgres",
+                connect_timeout=5,
+            )
+        except psycopg2.OperationalError:
+            pass
+        lines = drain()
+        assert_rfc5424(lines, service="postgres", event_type="startup")
+
+    def test_username_in_log(self, live_service):
+        port, drain = live_service("postgres")
+        import psycopg2
+        try:
+            psycopg2.connect(
+                host="127.0.0.1",
+                port=port,
+                user="dbattacker",
+                password="cracked",
+                dbname="secrets",
+                connect_timeout=5,
+            )
+        except psycopg2.OperationalError:
+            pass
+        lines = drain()
+        matched = assert_rfc5424(lines, service="postgres", event_type="startup")
+        assert "dbattacker" in matched, (
+            f"Expected username in log line. Got:\n{matched!r}"
+        )
+
+    def test_auth_hash_logged(self, live_service):
+        port, drain = live_service("postgres")
+        import psycopg2
+        try:
+            psycopg2.connect(
+                host="127.0.0.1",
+                port=port,
+                user="root",
+                password="toor",
+                dbname="prod",
+                connect_timeout=5,
+            )
+        except psycopg2.OperationalError:
+            pass
+        lines = drain()
+        assert_rfc5424(lines, service="postgres", event_type="auth")