test(sandbox): update v3 paths-aware tests for FR1+FR3 invariants

- test_paths.py: explicit initialize_paths(<empty_config>) instead of
  SLOP_CONFIG env var (v3 design); add restore_paths fixture so other
  tests keep their conftest workspace init.
- test_summary_cache.py: use tmp_path (under ./tests/) instead of
  hardcoded Path('.test_cache') that FR1 blocks.
- test_orchestrator_pm_history.py: use tempfile.mkdtemp() instead of
  writing to project-root 'test_conductor/' that FR1 blocks.
- test_gui_paths.py::test_save_paths: mock src.paths.initialize_paths
  instead of src.paths.reset_paths (v3 entry point).

All 12 tests pass in the Tier 2 clone after these fixes.

tests/test_orchestrator_pm_history.py

@@ -2,14 +2,16 @@ import unittest
 from unittest.mock import patch, MagicMock
 import shutil
 import json
+import tempfile
 from pathlib import Path
 from src import orchestrator_pm
 from src.result_types import Result
 
 class TestOrchestratorPMHistory(unittest.TestCase):
  def setUp(self) -> None:
-  self.test_dir = Path("test_conductor")
-  self.test_dir.mkdir(exist_ok=True)
+  # v3 paths.py: use tempdir (under system temp) for test data instead of
+  # writing to project-root "test_conductor/" which the FR1 guard blocks.
+  self.test_dir = Path(tempfile.mkdtemp(prefix="test_orch_"))
   self.archive_dir = self.test_dir / "archive"
   self.tracks_dir = self.test_dir / "tracks"
   self.archive_dir.mkdir(exist_ok=True)