feat: add Prism snake and gameplay database lifecycle

- Add bitboard-accelerated Prism and versioned Supreme snake implementations.
- Add database-backed move benchmarks and focused strategy tests.
- Normalize gameplay storage while preserving replay compatibility.
- Add deterministic game quality scoring and replay retention tiers.
- Add backup-first SQLite cleanup, verification, and replacement tooling.
- Add safe compact-plus-delta database merging with conflict detection.
- Extend SQLite and PostgreSQL schemas for replay and quality metadata.
- Add PostgreSQL development service and pytest import configuration.
- Update gameplay documentation and the quart_common submodule revision.

pyproject.toml

@@ -1,3 +1,7 @@
+[tool.pytest.ini_options]
+pythonpath = ["."]
+addopts = "--import-mode=importlib"
+
 [project]
 name = "snake-python"
 version = "0.1.0"