refactor: organize pilot packages

Group review, feedback, evaluation, observability, and entrypoint code into packages. Keep thin top-level compatibility shims for existing scripts and imports, and mirror the structure in the tests.

tests/pilot/conftest.py

@@ -0,0 +1,9 @@
+"""Make the pilot package roots available to every categorized test."""
+from __future__ import annotations
+
+import os
+import sys
+
+PILOT_ROOT = os.path.abspath(os.path.join(os.path.dirname(__file__), "..", "..", "pilot"))
+if PILOT_ROOT not in sys.path:
+    sys.path.insert(0, PILOT_ROOT)