feat(init): add preview_changes method to show read-only schema init diff

Adds preview_changes method to utils/neo4j-schema-init.py. Performs
read-only queries against the live database to compare current state
against the v2.3.0 schema spec. Reports expected constraints, indexes,
and sample nodes/relationships by team.

utils/pyproject.toml

@@ -0,0 +1,16 @@
+[project]
+name = "koios-utils"
+version = "0.1.0"
+description = "Operator scripts for the Koios unified Neo4j knowledge graph — schema init and validation"
+requires-python = ">=3.13"
+dependencies = [
+    "neo4j>=5.19,<6",
+]
+
+[build-system]
+requires = ["hatchling"]
+build-backend = "hatchling.build"
+
+[tool.hatch.build.targets.wheel]
+# These are operator scripts, not a library. Don't try to package them.
+bypass-selection = true