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.Assets.Generator.Tests/AssetHandlesGeneratorTests.cs

@@ -156,4 +156,33 @@ public class AssetHandlesGeneratorTests
     {
         Assert.Equal(expected, AssetHandlesGenerator.ToAssetPath(fullPath));
     }
+
+    [Theory]
+    [InlineData(@"D:\game\Assets\ui\Assets\icon.png", @"D:\game", "ui/Assets/icon.png")]
+    [InlineData(@"D:\game\Assets\icon.png", @"D:\game\", "icon.png")]
+    [InlineData(@"D:\game\Other\icon.png", @"D:\game", null)]
+    public void ToAssetPath_WithProjectDir_RootsAtProjectAssetsFolder(
+        string fullPath, string projectDir, string? expected)
+    {
+        Assert.Equal(expected, AssetHandlesGenerator.ToAssetPath(fullPath, projectDir));
+    }
+
+    [Fact]
+    public void SpecialCharactersInNames_AreEscapedInDocsAndLiterals()
+    {
+        var source = RunGenerator([@"D:\game\Assets\UI\a&b <c>.png"]);
+
+        Assert.Contains("a&amp;b &lt;c&gt;", source); // XML-док экранирован (иначе CS1570)
+        Assert.Contains("new(\"UI/a&b <c>.png\")", source);
+    }
+
+    [Fact]
+    public void FileNamedLikeContainerClass_DoesNotCollide()
+    {
+        // Член с именем вмещающего класса — ошибка CS0542; генератор должен переименовать.
+        var source = RunGenerator([@"D:\game\Assets\GameAssets.png"]);
+
+        Assert.Contains("GameAssets2 = new(\"GameAssets.png\")", source);
+        Assert.DoesNotContain("GameAssets = new(", source);
+    }
 }