Gauntlet #340: spec, package skeleton, scoring, six trials

Add the DESIGN.md (spec copy + implementation deviations), the trials package
(Trial base + ordered registry + six stress trials: entity swarm, animation
storm, grid titan, pathfinder rush, ui avalanche, sightline siege), and the
RampController/scoring logic. All pure Python under tests/benchmarks/gauntlet/.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

tests/benchmarks/gauntlet/trials/pathfinder_rush.py

@@ -0,0 +1,74 @@
+"""Trial 4: PATHFINDER RUSH -- A* query stress.
+
+A static maze grid; every tick issues Q grid.find_path queries between random
+walkable pairs. Load = queries per tick.
+"""
+import random
+
+import mcrfpy
+
+from . import Trial
+
+GRID_W, GRID_H = 60, 40
+CELL = 15
+ARENA_X, ARENA_Y = 60, 120
+
+
+class PathfinderRush(Trial):
+    key = "pathfinder_rush"
+    name = "PATHFINDER RUSH"
+    unit = "queries/tick"
+    accent = (76, 194, 110)
+    description = "A* find_path queries across a static maze"
+    base_load = 5
+    growth = 1.6
+
+    def setup(self, scene, ui):
+        super().setup(scene, ui)
+        self.rng = random.Random(0x9A2E)
+        self.queries = 0
+
+        grid = mcrfpy.Grid(grid_size=(GRID_W, GRID_H),
+                           pos=(ARENA_X, ARENA_Y),
+                           size=(GRID_W * CELL, GRID_H * CELL))
+        grid.zoom = CELL / 16.0
+        grid.fill_color = mcrfpy.Color(10, 14, 20)
+        floor = mcrfpy.ColorLayer(z_index=-1, name="floor")
+        grid.add_layer(floor)
+        floor.fill(mcrfpy.Color(40, 54, 44))
+
+        wall_c = mcrfpy.Color(14, 20, 16)
+        self.walkables = []
+        for y in range(GRID_H):
+            for x in range(GRID_W):
+                c = grid.at(x, y)
+                wall = (x == 0 or y == 0 or x == GRID_W - 1 or y == GRID_H - 1)
+                # Pillar/room maze: isolated blockers keep the map connected but windy.
+                if not wall and x % 4 == 2 and y % 3 == 1:
+                    wall = True
+                c.walkable = not wall
+                c.transparent = not wall
+                if wall:
+                    floor.set((x, y), wall_c)
+                else:
+                    self.walkables.append((x, y))
+        ui.append(grid)
+        self.grid = grid
+
+    def set_load(self, level_value):
+        self.queries = max(1, int(level_value))
+        self.load = self.queries
+
+    def tick(self, dt_ms):
+        if self.grid is None:
+            return
+        w = self.walkables
+        for _ in range(self.queries):
+            a = w[self.rng.randrange(len(w))]
+            b = w[self.rng.randrange(len(w))]
+            self.grid.find_path(a, b)
+
+    def teardown(self):
+        self.grid = None
+        self.walkables = []
+        super().teardown()