feat: add Zenith strategy and move latency tracing

- Register Zenith 1.1 with balanced duel verdicts and forced-outcome overrides.
- Prioritize permanent-trail space in Constrictor and health-aware hazard routes.
- Deduct executor queue delays and return fallback directions on move timeouts.
- Correlate response headers, replay timings, and sampled structured trace logs.
- Move shared metrics publication off the response path without losing local counts.
- Allow configurable tournament opponents and add a psql helper recipe.
- Preserve empty latency values through compact replay encoding and migration.
- Update Arena game links and use default assets for missing customizations.
- Cover strategy, HTTP lifecycle, tracing, replay codecs, and dashboard behavior.
- Validate with 260 passing Python tests, 4 skips, and 2 passing JavaScript tests.

tests/test_LegacyMigration.py

@@ -124,7 +124,7 @@ class TestLegacyMigration(unittest.TestCase):
       self.assertEqual((me["snake_id"], me["snake_name"], me["is_you"]), ("me", "Me", True))
       self.assertEqual((me["inferred_move"], me["latency"], me["health"], me["length"]), ("left", "12", 98, 3))
       enemy = turns[2]["snakes"][1]
-      self.assertEqual((enemy["inferred_move"], enemy["latency"]), ("down", None))
+      self.assertEqual((enemy["inferred_move"], enemy["latency"]), ("down", ""))
       with closing(sqlite3.connect(destination)) as connection:
         self.assertEqual(connection.execute("SELECT turn_count FROM game_replays").fetchone()[0], 3)