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.

tests/test_MergeGameplayDatabases.py

@@ -0,0 +1,93 @@
+import sqlite3
+import subprocess
+import sys
+import tempfile
+from pathlib import Path
+import unittest
+
+from server.database.backend.SqliteGameplayBackend import SqliteGameplayBackend
+
+class TestMergeGameplayDatabases(unittest.TestCase):
+  def _create_game(self, path:Path, game_id:str, winner_you:int, cleaned:bool=False) -> None:
+    SqliteGameplayBackend(str(path))
+    with sqlite3.connect(path) as connection:
+      connection.execute("""
+        INSERT INTO games (
+          game_id, started_at, ended_at, width, height, source, map_name,
+          ruleset_name, ruleset_version, your_snake_id, your_snake_name,
+          your_snake_type, your_snake_version, game_type, winner_name,
+          winner_you, final_turn, status, has_replay, quality_status,
+          quality_score, quality_tier, quality_reasons_json
+        ) VALUES (?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?,?)
+      """, (
+        game_id, "2026-01-01T00:00:00Z", "2026-01-01T00:01:00Z", 11, 11,
+        "league", "standard", "standard", "v1", "me", "PrismBattleSnake",
+        "PrismBattleSnake_GPT_5_6_Sol", "1.0.0", "duel", "PrismBattleSnake",
+        winner_you, 1, "finished", 1, "retained",
+        90 if cleaned else None, "high" if cleaned else None,
+        '["already_scored"]' if cleaned else None,
+      ))
+      connection.execute(
+        "INSERT INTO game_snakes (game_id,snake_id,snake_name,is_you) VALUES (?,?,?,?)",
+        (game_id, "me", "PrismBattleSnake", 1),
+      )
+      connection.execute("""
+        INSERT INTO turns (
+          game_id,turn,observed_at,my_move,my_thinking_json,
+          board_state_json,snakes_json,you_json,food_json,hazards_json
+        ) VALUES (?,?,?,?,?,?,?,?,?,?)
+      """, (game_id, 1, "2026-01-01T00:00:01Z", "up", '{"score":1}', '{}', '[]', '{}', '[]', '[]'))
+      connection.execute("""
+        INSERT INTO snake_turns (
+          game_id,turn,snake_id,health,length,head_x,head_y,body_json,is_you,inferred_move
+        ) VALUES (?,?,?,?,?,?,?,?,?,?)
+      """, (game_id, 1, "me", 90, 3, 1, 1, '[{"x":1,"y":1}]', 0, "up"))
+
+  def test_merges_base_and_delta_and_regenerates_row_ids(self):
+    with tempfile.TemporaryDirectory() as temp_dir:
+      root = Path(temp_dir)
+      base = root / "base.sqlite3"
+      delta = root / "delta.sqlite3"
+      merged = root / "merged.sqlite3"
+      self._create_game(base, "base-game", 1, cleaned=True)
+      self._create_game(delta, "delta-game", 0)
+
+      result = subprocess.run([
+        sys.executable, "scripts/merge_gameplay_databases.py",
+        "--base", str(base), "--delta", str(delta),
+        "--destination", str(merged), "--minimum-quality", "medium",
+      ], cwd=Path(__file__).resolve().parents[1], text=True, capture_output=True)
+
+      self.assertEqual(result.returncode, 0, result.stderr)
+      with sqlite3.connect(merged) as connection:
+        games = connection.execute(
+          "SELECT game_id, winner_you, has_replay, quality_tier FROM games ORDER BY game_id"
+        ).fetchall()
+        self.assertEqual(games, [
+          ("base-game", 1, 1, "high"),
+          ("delta-game", 0, 1, "medium"),
+        ])
+        self.assertEqual(connection.execute("SELECT COUNT(*) FROM turns").fetchone()[0], 2)
+        self.assertEqual(connection.execute("SELECT COUNT(*) FROM snake_turns").fetchone()[0], 2)
+        self.assertEqual(connection.execute("PRAGMA foreign_key_check").fetchall(), [])
+
+  def test_conflicting_duplicate_aborts_without_destination(self):
+    with tempfile.TemporaryDirectory() as temp_dir:
+      root = Path(temp_dir)
+      base = root / "base.sqlite3"
+      delta = root / "delta.sqlite3"
+      merged = root / "merged.sqlite3"
+      self._create_game(base, "same-game", 1, cleaned=True)
+      self._create_game(delta, "same-game", 0)
+
+      result = subprocess.run([
+        sys.executable, "scripts/merge_gameplay_databases.py",
+        "--base", str(base), "--delta", str(delta), "--destination", str(merged),
+      ], cwd=Path(__file__).resolve().parents[1], text=True, capture_output=True)
+
+      self.assertNotEqual(result.returncode, 0)
+      self.assertIn("Conflicting duplicate game_id", result.stderr)
+      self.assertFalse(merged.exists())
+
+if __name__ == "__main__":
+  unittest.main()