chore: prune unused imports and duplicate import redefinitions

Remove unused imports (F401) and duplicate/shadowed import
redefinitions (F811) across the codebase using ruff's safe
autofixes. No behavioral changes -- imports only.

- ~1400 safe autofixes applied across 644 files (net -1072 lines)
- __init__.py re-exports preserved (excluded from F401 removal so
  public re-export surfaces stay intact)
- Re-exports that are imported or monkeypatched by tests but look
  unused in their defining module are kept with explicit # noqa:
  F401 (gateway/run.py load_dotenv; run_agent re-exports from
  agent.message_sanitization, agent.context_compressor,
  agent.retry_utils, agent.prompt_builder, agent.process_bootstrap,
  agent.codex_responses_adapter)
- Unsafe F841 (unused-variable) fixes deliberately skipped -- those
  can change behavior when the RHS has side effects
- ruff lints remain disabled in pyproject.toml (only PLW1514 is
  selected); this is a one-time cleanup, not a config change

Verification:
- python -m compileall: clean
- pytest --collect-only: all 27161 tests collect (zero import errors)
- core entry points import clean (run_agent, model_tools, cli,
  toolsets, hermes_state, batch_runner, gateway)
- static scan: every name any test imports directly from an edited
  module still resolves

tests/cron/test_cron_context_from.py

@@ -45,7 +45,7 @@ class TestJobContextFromField:
         assert loaded["context_from"] == [job_a["id"]]
 
     def test_create_job_with_context_from_list(self, cron_env):
-        from cron.jobs import create_job, get_job
+        from cron.jobs import create_job
 
         job_a = create_job(prompt="Find news", schedule="every 1h")
         job_b = create_job(prompt="Find weather", schedule="every 1h")

tests/cron/test_cron_inactivity_timeout.py

@@ -12,11 +12,8 @@ import concurrent.futures
 import os
 import sys
 import time
-import threading
 from pathlib import Path
-from unittest.mock import MagicMock, patch
 
-import pytest
 
 # Ensure project root is importable
 sys.path.insert(0, str(Path(__file__).parent.parent.parent))

tests/cron/test_cron_no_agent.py

@@ -12,7 +12,6 @@ Covers:
 from __future__ import annotations
 
 import json
-from pathlib import Path
 from unittest.mock import patch
 
 import pytest

tests/cron/test_cron_profile.py

@@ -8,7 +8,6 @@ from __future__ import annotations
 
 import json
 import os
-from pathlib import Path
 
 import pytest
 

tests/cron/test_cron_script.py

@@ -9,11 +9,9 @@ Tests cover:
 
 import json
 import os
-import stat
 import sys
 import textwrap
 from pathlib import Path
-from unittest.mock import patch
 
 import pytest
 

tests/cron/test_cron_workdir.py

@@ -13,7 +13,6 @@ Covers:
 from __future__ import annotations
 
 import json
-from pathlib import Path
 
 import pytest
 

tests/cron/test_file_permissions.py

@@ -1,6 +1,5 @@
 """Tests for file permissions hardening on sensitive files."""
 
-import json
 import os
 import stat
 import tempfile

tests/cron/test_jobs.py

@@ -1,11 +1,8 @@
 """Tests for cron/jobs.py — schedule parsing, job CRUD, and due-job detection."""
 
-import json
 import threading
 import pytest
 from datetime import datetime, timedelta, timezone
-from pathlib import Path
-from unittest.mock import patch
 
 from cron.jobs import (
     parse_duration,

tests/cron/test_scheduler.py

@@ -1275,7 +1275,6 @@ class TestRunJobSessionPersistence:
         (issue #8585)
         """
         from cron.scheduler import tick
-        from cron.jobs import load_jobs, save_jobs
 
         job = {
             "id": "empty-job",
@@ -2300,7 +2299,6 @@ class TestParallelTick:
     def test_parallel_jobs_run_concurrently(self):
         """Two jobs launched in the same tick should overlap in time."""
         import threading
-        import time
 
         barrier = threading.Barrier(2, timeout=5)
         call_order = []

tests/cron/test_scheduler_mcp_init.py

@@ -15,9 +15,8 @@ short-circuit on already-connected servers.
 
 from __future__ import annotations
 
-from unittest.mock import patch, MagicMock
+from unittest.mock import patch
 
-import pytest