feat(ui): debug overlay + refined input controls

Adds the first on-screen HUD for the dev client plus today's mouse-control
refinements. Also lands yesterday's scenery-alignment changes that were
left uncommitted in the working tree.

Overlay:
- BitmapFont rasterizes a system TTF via StbTrueTypeSharp into a 512x512
  R8 atlas at startup (Consolas on Windows, DejaVu/Menlo fallbacks)
- TextRenderer batches 2D quads in screen-space with ortho projection;
  one shader + two draw calls (rect then text) for panel backgrounds
  under glyphs
- DebugOverlay composes info / stats / compass / help panels on top of
  the 3D scene; toggles via F1/F4/F5/F6; transient toasts for key events
- DebugLineRenderer and its shaders (carried over from the scenery work)
  are properly committed in this commit

Controls:
- Per-mode mouse sensitivity (Chase 0.15, Fly 1.0, Orbit 1.0); F8/F9 to
  adjust the active mode multiplicatively (x1.2)
- Hold RMB to free-orbit the chase camera around the player; release
  stays at the new angle (no snap-back)
- Mouse-wheel zooms chase distance between 2m and 40m
- Chase pitch widened to [-0.7, 1.4] so mouse-Y tilts both ways from
  the default neutral angle

Scenery alignment (carried from yesterday's session):
- ShadowObjectRegistry AllEntriesForDebug + Scale field
- SceneryGenerator uses ACViewer's OnRoad polygon test + baseLoc +
  set_heading rotation
- BSPQuery dispatchers accept localToWorld so normals/offsets transform
  correctly per part
- TransitionTypes.CylinderCollision rewritten with wall-slide + push-out
- PhysicsDataCache caches visual-mesh AABB for scenery that lacks
  physics Setup bounds

src/AcDream.Core/World/WorldEntity.cs

@@ -43,4 +43,16 @@ public sealed class WorldEntity
     /// Null for outdoor entities (stabs, scenery, live server spawns).
     /// </summary>
     public uint? ParentCellId { get; init; }
+
+    /// <summary>
+    /// Uniform scale applied to this entity's mesh by the scenery pipeline.
+    /// For scenery objects this is spawn.Scale (typically 0.8–1.3). For stabs
+    /// and interior static objects this is 1.0 (no scaling).
+    ///
+    /// Used by the collision registration path to scale CylSphere / Sphere /
+    /// Setup.Radius shapes so they match the visually-scaled mesh. Without
+    /// this, scaled scenery has a collision cylinder that's smaller than the
+    /// visible trunk, producing "partial passthrough" bugs.
+    /// </summary>
+    public float Scale { get; init; } = 1.0f;
 }