Add full day night survival QA gate

Docs/QA/MvpQaGates.md

@@ -125,3 +125,32 @@ Required evidence:
 
 This gate is gameplay/server-relevant and should be covered by the next server
 package deployment.
+
+## Full Day/Night Survival
+
+The full day/night survival gate proves one player can remain alive through one
+complete compressed Agrarian day while the server advances time, weather, and
+survival pressure.
+
+MVP timing:
+
+- The gameplay calendar target is `4 real hours = 1 in-game day`.
+- `AAgrarianGameState` advances and replicates `WorldHours`, day/year state,
+  solar bounds, `IsNight`, weather, and ambient temperature.
+- The pass starts at a known hour, preferably dawn or morning, and ends after
+  `WorldHours` reaches the same solar phase on the next in-game day.
+
+Required evidence:
+
+- Hunger, thirst, stamina, body temperature, and health update over time on
+  server authority.
+- A player can gather resources, craft or use a fire, craft or use shelter,
+  and recover enough food/water/warmth to avoid death for the full cycle.
+- Day/night state changes at least once and returns to the original phase.
+- The critical survival HUD can show alive/dead state and core stat pressure.
+- World time and player survival state are covered by save/load persistence.
+- The result is recorded as either a completed manual run or a captured test
+  log before external MVP demos treat the gate as fully play-proven.
+
+This gate is gameplay/server-relevant and should be covered by the next server
+package deployment.