feat: add live replays and PostgreSQL maintenance tools

- Stream compact live replay updates across local and clustered dashboards.
- Render responsive snake bodies as SVG paths with aligned custom icons.
- Add cache-busted assets, replay fallback routes, and live-follow playback.
- Support PostgreSQL benchmark sampling and idempotent SQLite migration.
- Add dry-run cleanup for old low-quality PostgreSQL replay payloads.
- Reward safe perimeter lanes and bump Prism to version 1.5.0.
- Add backend, migration, dashboard, and perimeter regression coverage.

tests/snakes/test_PerimeterScoring.py

@@ -0,0 +1,51 @@
+import unittest
+
+from snakes.engine.perimeter import perimeter_geometry_score
+
+class TestPerimeterGeometryScore(unittest.TestCase):
+  def score(self, point, **overrides):
+    values = {
+      "point": point,
+      "current_head": (0, 5),
+      "width": 11,
+      "height": 11,
+      "occupancy": 0.35,
+      "snake_length": 12,
+      "reachable_space": 80,
+      "required_space": 12,
+      "liberties": 2,
+      "next_options": 2,
+      "safe_next_options": 2,
+      "tail_escape": True,
+      "dead_end": False,
+      "losing_head_to_head": False,
+    }
+    values.update(overrides)
+    return perimeter_geometry_score(**values)
+
+  def test_safe_wall_lane_can_outscore_adjacent_inner_lane(self):
+    wall = self.score((0, 6))
+    inner = self.score((1, 5))
+
+    self.assertGreater(wall, inner)
+
+  def test_unsafe_wall_does_not_receive_perimeter_reward(self):
+    safe_wall = self.score((0, 6))
+    unsafe_wall = self.score((0, 6), safe_next_options=1)
+
+    self.assertGreater(safe_wall, unsafe_wall + 30.0)
+
+  def test_corner_is_less_attractive_than_straight_edge(self):
+    corner = self.score((0, 0), current_head=(0, 1))
+    straight_edge = self.score((0, 6))
+
+    self.assertGreater(straight_edge, corner)
+
+  def test_losing_head_to_head_never_gets_perimeter_reward(self):
+    safe_wall = self.score((0, 6))
+    contested_wall = self.score((0, 6), losing_head_to_head=True)
+
+    self.assertGreater(safe_wall, contested_wall + 30.0)
+
+if __name__ == "__main__":
+  unittest.main()

tests/snakes/test_PrismBattleSnake_GPT_5_6_Sol.py

@@ -52,8 +52,8 @@ class TestPrismBattleSnake_GPT_5_6_Sol(unittest.TestCase):
     snake = PrismBattleSnake_GPT_5_6_Sol()
 
     self.assertEqual(snake.name, "PrismBattleSnake")
-    self.assertEqual(snake.version, "1.4.0")
-    self.assertEqual(get_snake_version("PrismBattleSnake_GPT_5_6_Sol"), "1.4.0")
+    self.assertEqual(snake.version, "1.5.0")
+    self.assertEqual(get_snake_version("PrismBattleSnake_GPT_5_6_Sol"), "1.5.0")
     self.assertGreaterEqual(snake._planning_depth, 4)
     self.assertIsInstance(SnakeBuilder.build("PrismBattleSnake_GPT_5_6_Sol"), PrismBattleSnake_GPT_5_6_Sol)