Implement canonical pricing core and close WP-0003

projects/coulomb-pricing/observatory/_repo_root.py

@@ -0,0 +1,12 @@
+from __future__ import annotations
+
+import sys
+from pathlib import Path
+
+REPO_ROOT = Path(__file__).resolve().parents[3]
+
+
+def ensure_repo_root_on_syspath() -> None:
+    root = str(REPO_ROOT)
+    if root not in sys.path:
+        sys.path.insert(0, root)