fix(streaming): reload terrain on an outdoor teleport (sky-arcs)

Terrain vertices are baked into the GPU relative to the render origin (_liveCenter),
which only moves on a teleport. A FAR jump unloads/reloads everything → fine. But a
NEARBY outdoor jump (e.g. (170,168)->(169,180), 12 landblocks) leaves the old and new
streaming windows overlapping, so StreamingRegion.RecenterTo KEEPS the ~330 overlapping
blocks (correct — they're in the new window) — yet they still hold vertices baked at the
OLD origin. The instant _liveCenter moves they render shifted by the jump distance: a
band of terrain hanging in the sky ("terrain in the sky" arcs). Confirmed by probe: every
stale slot was offset by EXACTLY deltaLB*192 ((-1,12)*192 = (-192,2304)), 330 of them
persisting after the hop.

Fix: StreamingController.ForceReloadWindow() — on an OUTDOOR teleport, SYNCHRONOUSLY drop
every resident landblock (render slot + physics + state) so none survives the frame stale,
then null the region so NormalTick re-bootstraps the whole window fresh at the new origin
(the near ring is priority-applied behind the fade; the rest streams). Called from
OnLivePositionUpdated's outdoor recenter branch; sealed dungeons keep PreCollapseToDungeon.

Verified live: the exact nearby hop that produced 330 stale slots now produces 0 across
the whole session, and the horizon is clean.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/AcDream.App/Rendering/GameWindow.cs

@@ -5470,6 +5470,12 @@ public sealed class GameWindow : IDisposable
                 // player position can't drift the observer off the dungeon and re-expand.
                 if (_streamingController is not null && IsSealedDungeonCell(p.LandblockId))
                     _streamingController.PreCollapseToDungeon(lbX, lbY);
+                else
+                    // Outdoor teleport: the render origin (_liveCenter) just moved. Drop ALL
+                    // resident terrain so overlapping blocks on a NEARBY jump re-bake at the
+                    // new origin instead of rendering shifted — the confirmed "terrain in the
+                    // sky" arcs (stale slots offset by exactly deltaLB×192). 2026-06-22.
+                    _streamingController?.ForceReloadWindow();
             }
             else
             {

src/AcDream.App/Streaming/StreamingController.cs

@@ -344,6 +344,31 @@ public sealed class StreamingController
         _region = rebuilt;
     }
 
+    /// <summary>
+    /// 2026-06-22: an OUTDOOR teleport moved the render origin (<c>_liveCenter</c>). Every
+    /// resident terrain block was baked relative to the OLD origin, so any block that survives
+    /// an INCREMENTAL recenter — which happens on a NEARBY jump where the old and new windows
+    /// overlap, e.g. (170,168)→(169,180) — renders shifted by the jump distance: the confirmed
+    /// "terrain in the sky" arcs (the stale slots were all offset by exactly deltaLB×192).
+    /// SYNCHRONOUSLY drop every resident landblock (render slot + physics + state) so none
+    /// survives into the next frame stale, and no async unload can race a re-bake, then null
+    /// the region so the next <see cref="NormalTick"/> re-bootstraps the WHOLE window fresh at
+    /// the new origin (the near ring is priority-applied behind the fade; the rest streams in).
+    /// A sealed-dungeon destination uses <see cref="PreCollapseToDungeon"/> instead.
+    /// </summary>
+    public void ForceReloadWindow()
+    {
+        _collapsed = false;
+        // Snapshot — RemoveLandblock mutates the loaded set we're iterating.
+        var ids = new List<uint>(_state.LoadedLandblockIds);
+        foreach (var id in ids)
+        {
+            _state.RemoveLandblock(id);
+            _removeTerrain?.Invoke(id);   // frees the render slot + physics + cell registries
+        }
+        _region = null;   // NormalTick re-creates + bootstraps the full window next frame
+    }
+
     /// <summary>
     /// Apply streamed completions for this frame. LOADS (terrain mesh GPU uploads) are the
     /// expensive part, so they are metered at <see cref="MaxCompletionsPerFrame"/> to avoid a