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_imap_live.py

@@ -0,0 +1,80 @@
+import imaplib
+
+import pytest
+
+from tests.live.conftest import assert_rfc5424
+
+
+@pytest.mark.live
+class TestIMAPLive:
+    def test_banner_received(self, live_service):
+        port, drain = live_service("imap")
+        imap = imaplib.IMAP4("127.0.0.1", port)
+        welcome = imap.welcome.decode()
+        imap.logout()
+        assert "OK" in welcome
+
+    def test_connect_logged(self, live_service):
+        port, drain = live_service("imap")
+        imap = imaplib.IMAP4("127.0.0.1", port)
+        imap.logout()
+        lines = drain()
+        assert_rfc5424(lines, service="imap", event_type="connect")
+
+    def test_login_logged(self, live_service):
+        port, drain = live_service("imap")
+        imap = imaplib.IMAP4("127.0.0.1", port)
+        try:
+            imap.login("admin", "wrongpass")
+        except imaplib.IMAP4.error:
+            pass
+        lines = drain()
+        try:
+            imap.logout()
+        except Exception:
+            pass
+        lines += drain()
+        assert_rfc5424(lines, service="imap", event_type="auth")
+
+    def test_auth_success_logged(self, live_service):
+        port, drain = live_service("imap")
+        imap = imaplib.IMAP4("127.0.0.1", port)
+        imap.login("admin", "admin123")  # valid cred from IMAP_USERS default
+        lines = drain()
+        imap.logout()
+        lines += drain()
+        matched = assert_rfc5424(lines, service="imap", event_type="auth")
+        assert "success" in matched, f"Expected auth success in log. Got:\n{matched!r}"
+
+    def test_auth_fail_logged(self, live_service):
+        port, drain = live_service("imap")
+        imap = imaplib.IMAP4("127.0.0.1", port)
+        try:
+            imap.login("hacker", "crackedpassword")
+        except imaplib.IMAP4.error:
+            pass  # expected
+        lines = drain()
+        try:
+            imap.logout()
+        except Exception:
+            pass
+        lines += drain()
+        matched = assert_rfc5424(lines, service="imap", event_type="auth")
+        assert "failed" in matched, f"Expected auth failure in log. Got:\n{matched!r}"
+
+    def test_select_inbox_after_login(self, live_service):
+        port, drain = live_service("imap")
+        imap = imaplib.IMAP4("127.0.0.1", port)
+        imap.login("admin", "admin123")
+        status, data = imap.select("INBOX")
+        imap.logout()
+        assert status == "OK", f"SELECT INBOX failed: {data}"
+
+    def test_capability_command(self, live_service):
+        port, drain = live_service("imap")
+        imap = imaplib.IMAP4("127.0.0.1", port)
+        status, caps = imap.capability()
+        imap.logout()
+        assert status == "OK"
+        cap_str = b" ".join(caps).decode()
+        assert "IMAP4rev1" in cap_str