Fix engine-wide code review findings

Collisions: init bucket heads to -1 (QueryAabb hung before the first
rebuild), reset query stamps on truncated QueryAabb (later queries
silently dropped entities), inside-origin raycasts hit at fraction 0 for
circles too, exactly-touching boxes now pair like touching circles.

Graphics: render into the letterbox viewport so the picture matches
ScreenToWorld/WorldToScreen instead of stretching; Y-sort by the
transform pivot rather than the quad center; lock-free snapshot
LayerRegistry (parallel submit read it unsynchronized); validate
InitialCapacity; warn when UseRenderer2D drops options of a later scene.

Core: scenes are explicitly single-use (re-loading threw silently
duplicated systems/entities before — now it throws), Scene.RegisterUnload
for per-scene resources, a switch requested during the reveal phase
covers again instead of hard-swapping, borderless fullscreen
(HardwareModeSwitch off), InputCapture service for input-suppressing
overlays, host disposes the transition renderer and IDisposable services
on shutdown.

Input: game input reads as released while InputCapture is held; mouse
position and wheel freeze so deltas stay zero.

DevConsole: holds InputCapture while open (typing no longer drives the
camera), Revision increments only under the lock, quoted command
arguments, history capped at 256.

UI: scene Desktop skips Myra input processing while the console is open
(clicks no longer fall through), is disposed on scene unload, and Myra
init no longer depends on a process-static flag.

Audio: validate channel count/sample rate before stopping the previous
track, empty looped oggs no longer hang FillBuffers, the instance stops
when a non-looping track drains (IsPlaying was stuck true).

Atlases: metadata v2 stores per-source size+mtime snapshots, so
timestamp-preserving copies and renames invalidate correctly; loader
checks the version and disposes pages on partial load failure; shared
pages never exceed a non-POT MaxPageSize; oversized items pack first
onto exact-size pages instead of splitting an open shared page; the CLI
validates numeric options.

Assets.Generator: file names are escaped in XML docs and string
literals, members no longer collide with the enclosing class (CS0542),
and the Assets root is resolved against build_property.projectdir so
nested "Assets" directories do not shift region paths.

Pathfinding: queries throw when the grid was resized after construction;
generation stamps survive int overflow.

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

tests/MrGameEng.Collisions.Tests/CollisionWorldTests.cs

@@ -182,4 +182,59 @@ public class CollisionWorldTests
 
         Assert.False(scene.World.Raycast(new Vector2(0f, 0f), new Vector2(100f, 0f), out _));
     }
+
+    [Fact]
+    public void QueryAabb_BeforeFirstRebuild_ReturnsZero()
+    {
+        // До первого EndRebuild хэш пуст; запрос не должен зависать и что-то находить.
+        var world = new CollisionWorld();
+
+        Span<Entity> results = new Entity[4];
+        Assert.Equal(0, world.QueryAabb(new RectF(-10f, -10f, 20f, 20f), results));
+    }
+
+    [Fact]
+    public void QueryAabb_TruncatedResults_DoNotPoisonNextQuery()
+    {
+        var (context, scene) = CreateScene();
+        for (var i = 0; i < 3; i++)
+        {
+            Spawn(scene, new Vector2(i * 5f, 0f), Collider.Circle(4f));
+        }
+
+        Tick(context);
+
+        var area = new RectF(-10f, -10f, 40f, 20f);
+        Span<Entity> tiny = new Entity[1];
+        Assert.Equal(1, scene.World.QueryAabb(area, tiny)); // обрезан по размеру буфера
+
+        Span<Entity> all = new Entity[8];
+        Assert.Equal(3, scene.World.QueryAabb(area, all)); // повторный запрос видит всех
+    }
+
+    [Fact]
+    public void Raycast_FromInsideCircle_HitsAtOrigin()
+    {
+        var (context, scene) = CreateScene();
+        var entity = Spawn(scene, new Vector2(0f, 0f), Collider.Circle(10f));
+
+        Tick(context);
+
+        Assert.True(scene.World.Raycast(new Vector2(0f, 0f), new Vector2(100f, 0f), out var hit));
+        Assert.Equal(entity, hit.Entity);
+        Assert.Equal(0f, hit.Fraction);
+        Assert.Equal(Vector2.Zero, hit.Point);
+    }
+
+    [Fact]
+    public void ExactlyTouchingBoxes_ProducePair()
+    {
+        var (context, scene) = CreateScene();
+        Spawn(scene, new Vector2(0f, 0f), Collider.Box(20f, 20f));
+        Spawn(scene, new Vector2(20f, 0f), Collider.Box(20f, 20f)); // грани соприкасаются ровно
+
+        Tick(context);
+
+        Assert.Equal(1, scene.World.Pairs.Length); // как и у касающихся кругов
+    }
 }