fix: resolve all ruff lint errors and SQLite UNIQUE constraint issue

Ruff fixes (20 errors → 0):
- F401: Remove unused imports (DeckyConfig, random_hostname, IniConfig,
  COMPOSE_FILE, sys, patch) across cli.py, mutator/engine.py,
  templates/ftp, templates/rdp, test_mysql.py, test_postgres.py
- F541: Remove extraneous f-prefixes on strings with no placeholders
  in templates/imap, test_ftp_live, test_http_live
- E741: Rename ambiguous variable 'l' to descriptive names (line, entry,
  part) across conftest.py, test_ftp_live, test_http_live,
  test_mongodb_live, test_pop3, test_ssh

SQLite fix:
- Change _initialize_sync() admin seeding from SELECT-then-INSERT to
  INSERT OR IGNORE, preventing IntegrityError when admin user already
  exists from a previous run

tests/live/conftest.py

@@ -83,7 +83,7 @@ def assert_rfc5424(
     criteria = {"service": service, "event_type": event_type, **fields}
     raise AssertionError(
         f"No RFC 5424 line matching {criteria!r} found among {len(lines)} lines:\n"
-        + "\n".join(f"  {l!r}" for l in lines[:20])
+        + "\n".join(f"  {line!r}" for line in lines[:20])
     )
 
 

tests/live/test_ftp_live.py

@@ -35,5 +35,5 @@ class TestFTPLive:
         ftp.close()
         lines = drain()
         # At least one RFC 5424 line from the ftp service
-        rfc_lines = [l for l in lines if "<" in l and ">1 " in l and "ftp" in l]
-        assert rfc_lines, f"No ftp RFC 5424 lines found. stdout:\n" + "\n".join(lines[:15])
+        rfc_lines = [line for line in lines if "<" in line and ">1 " in line and "ftp" in line]
+        assert rfc_lines, "No ftp RFC 5424 lines found. stdout:\n" + "\n".join(lines[:15])

tests/live/test_http_live.py

@@ -28,8 +28,8 @@ class TestHTTPLive:
         )
         lines = drain()
         # body field present in log line
-        assert any("body=" in l for l in lines if "request" in l), (
-            f"Expected 'body=' in request log line. Got:\n" + "\n".join(lines[:10])
+        assert any("body=" in line for line in lines if "request" in line), (
+            "Expected 'body=' in request log line. Got:\n" + "\n".join(lines[:10])
         )
 
     def test_method_and_path_in_log(self, live_service):

tests/live/test_mongodb_live.py

@@ -65,6 +65,6 @@ class TestMongoDBLive:
             client.close()
         lines = drain()
         # At least one message was exchanged
-        assert any("mongodb" in l for l in lines), (
+        assert any("mongodb" in line for line in lines), (
             "Expected at least one mongodb log line"
         )

tests/service_testing/test_mysql.py

@@ -8,7 +8,7 @@ length fields that could cause huge buffer allocations.
 import importlib.util
 import struct
 import sys
-from unittest.mock import MagicMock, patch
+from unittest.mock import MagicMock
 
 import pytest
 from hypothesis import given, settings

tests/service_testing/test_pop3.py

@@ -176,7 +176,7 @@ def test_pop3_list_returns_10_entries(pop3_mod):
     resp = _replies(written).decode()
     assert resp.startswith("+OK 10")
     # Count individual message lines: "N size\r\n"
-    entries = [l for l in resp.split("\r\n") if l and l[0].isdigit()]
+    entries = [entry for entry in resp.split("\r\n") if entry and entry[0].isdigit()]
     assert len(entries) == 10
 
 
@@ -225,7 +225,7 @@ def test_pop3_top_3_body_lines_count(pop3_mod):
     parts = resp.split("\r\n\r\n", 1)
     assert len(parts) == 2
     body_section = parts[1].rstrip("\r\n.")
-    body_lines = [l for l in body_section.split("\r\n") if l != "."]
+    body_lines = [part for part in body_section.split("\r\n") if part != "."]
     assert len(body_lines) <= 3
 
 
@@ -235,7 +235,7 @@ def test_pop3_uidl_returns_10_entries(pop3_mod):
     _send(proto, "UIDL")
     resp = _replies(written).decode()
     assert resp.startswith("+OK")
-    entries = [l for l in resp.split("\r\n") if l and l[0].isdigit()]
+    entries = [entry for entry in resp.split("\r\n") if entry and entry[0].isdigit()]
     assert len(entries) == 10
 
 

tests/service_testing/test_postgres.py

@@ -8,7 +8,7 @@ tests for zero/tiny/huge msg_len in both the startup and auth states.
 import importlib.util
 import struct
 import sys
-from unittest.mock import MagicMock, patch
+from unittest.mock import MagicMock
 
 import pytest
 from hypothesis import given, settings

tests/test_ssh.py

@@ -112,8 +112,8 @@ def test_dockerfile_has_rsyslog():
 
 
 def test_dockerfile_runs_as_root():
-    lines = [l.strip() for l in _dockerfile_text().splitlines()]
-    user_lines = [l for l in lines if l.startswith("USER ")]
+    lines = [line.strip() for line in _dockerfile_text().splitlines()]
+    user_lines = [line for line in lines if line.startswith("USER ")]
     assert user_lines == [], f"Unexpected USER directive(s): {user_lines}"