chore(lint): apply ruff --fix (4443 auto-fixes)

Auto-fixed categories:
- F401: unused imports removed
- I001: import blocks sorted
- W293: trailing whitespace stripped
- UP035: deprecated typing imports replaced
- SIM: simplify suggestions applied
- ARG: unused args prefixed with underscore
- T201: print statements removed
- F841: unused variables removed
- RUF059: unpacked variables prefixed

Remaining ~1500 unfixable errors (C901, B904, N806, E402) require manual work.

Backend smoke tests: 13/13 passed.

backend/tests/scripts/test_clean_release_cli.py

@@ -5,21 +5,19 @@
 
 """Smoke tests for the redesigned clean release CLI commands."""
 
+from datetime import UTC, datetime
 from types import SimpleNamespace
-import json
-
-from src.dependencies import get_clean_release_repository, get_config_manager
-from datetime import datetime, timezone
 from uuid import uuid4
 
+from src.dependencies import get_clean_release_repository, get_config_manager
 from src.models.clean_release import (
     CleanPolicySnapshot,
     ComplianceReport,
     ReleaseCandidate,
     SourceRegistrySnapshot,
 )
-from src.services.clean_release.enums import CandidateStatus, ComplianceDecision
 from src.scripts.clean_release_cli import main as cli_main
+from src.services.clean_release.enums import CandidateStatus, ComplianceDecision
 
 
 # [DEF:test_cli_candidate_register_scaffold:Function]
@@ -227,7 +225,7 @@ def test_cli_release_gate_commands_scaffold() -> None:
             version="1.0.0",
             source_snapshot_ref="git:sha-approved",
             created_by="cli-test",
-            created_at=datetime.now(timezone.utc),
+            created_at=datetime.now(UTC),
             status=CandidateStatus.CHECK_PASSED.value,
         )
     )
@@ -237,7 +235,7 @@ def test_cli_release_gate_commands_scaffold() -> None:
             version="1.0.0",
             source_snapshot_ref="git:sha-rejected",
             created_by="cli-test",
-            created_at=datetime.now(timezone.utc),
+            created_at=datetime.now(UTC),
             status=CandidateStatus.CHECK_PASSED.value,
         )
     )
@@ -252,7 +250,7 @@ def test_cli_release_gate_commands_scaffold() -> None:
                 "violations_count": 0,
                 "blocking_violations_count": 0,
             },
-            generated_at=datetime.now(timezone.utc),
+            generated_at=datetime.now(UTC),
             immutable=True,
         )
     )
@@ -267,7 +265,7 @@ def test_cli_release_gate_commands_scaffold() -> None:
                 "violations_count": 0,
                 "blocking_violations_count": 0,
             },
-            generated_at=datetime.now(timezone.utc),
+            generated_at=datetime.now(UTC),
             immutable=True,
         )
     )

backend/tests/scripts/test_clean_release_tui.py

@@ -5,17 +5,16 @@
 # @LAYER: Scripts
 # @INVARIANT: TUI initializes, handles hotkeys (F5, F10) and safely falls back without TTY.
 
-import os
-import sys
 import curses
 import json
+import os
 from unittest import mock
 from unittest.mock import MagicMock, patch
 
 import pytest
 
-from src.scripts.clean_release_tui import CleanReleaseTUI, main, tui_main
 from src.models.clean_release import CheckFinalStatus
+from src.scripts.clean_release_tui import CleanReleaseTUI, main
 
 
 @pytest.fixture
@@ -63,17 +62,17 @@ def test_tui_initial_render(mock_curses_module, mock_stdscr: MagicMock):
 
     app = CleanReleaseTUI(mock_stdscr)
     assert app.status == "READY"
-    
+
     # We only want to run one loop iteration, so we mock getch to return F10
     mock_stdscr.getch.return_value = curses.KEY_F10
-    
+
     app.loop()
-    
+
     # Assert header was drawn
     addstr_calls = mock_stdscr.addstr.call_args_list
     assert any("Enterprise Clean Release Validator" in str(call) for call in addstr_calls)
     assert any("Candidate: [2026.03.03-rc1]" in str(call) for call in addstr_calls)
-    
+
     # Assert checks list is shown
     assert any("Data Purity" in str(call) for call in addstr_calls)
     assert any("Internal Sources Only" in str(call) for call in addstr_calls)
@@ -98,7 +97,7 @@ def test_tui_run_checks_f5(mock_curses_module, mock_stdscr: MagicMock):
     mock_curses_module.A_BOLD = 0
 
     app = CleanReleaseTUI(mock_stdscr)
-    
+
     # getch sequence:
     # 1. First loop: F5 (triggers run_checks)
     # 2. Next call after run_checks: F10 to exit
@@ -108,12 +107,12 @@ def test_tui_run_checks_f5(mock_curses_module, mock_stdscr: MagicMock):
             mock_stdscr.f5_pressed = True
             return curses.KEY_F5
         return curses.KEY_F10
-    
+
     mock_stdscr.getch.side_effect = side_effect
-    
+
     with mock.patch("time.sleep", return_value=None):
         app.loop()
-    
+
     # After F5 is pressed, status should be BLOCKED due to deliberate 'test-data' violation
     assert app.status == CheckFinalStatus.BLOCKED
     assert app.report_id is not None
@@ -132,13 +131,13 @@ def test_tui_exit_f10(mock_curses_module, mock_stdscr: MagicMock):
     """
     # Ensure constants match
     mock_curses_module.KEY_F10 = curses.KEY_F10
-    
+
     app = CleanReleaseTUI(mock_stdscr)
     mock_stdscr.getch.return_value = curses.KEY_F10
-    
+
     # loop() should return cleanly
     app.loop()
-    
+
     assert app.status == "READY"
 
 
@@ -159,12 +158,12 @@ def test_tui_clear_history_f7(mock_curses_module, mock_stdscr: MagicMock):
     app = CleanReleaseTUI(mock_stdscr)
     app.status = CheckFinalStatus.BLOCKED
     app.report_id = "SOME-REPORT"
-    
+
     # F7 then F10
     mock_stdscr.getch.side_effect = [curses.KEY_F7, curses.KEY_F10]
-    
+
     app.loop()
-    
+
     assert app.status == "READY"
     assert app.report_id is None
     assert len(app.checks_progress) == 0