refactor(lifetime): own render resource prefixes

Give terrain, sky, retained UI, portal preparation, and the update/render frame pair explicit single owners. Make shader, texture, text, bindless, and GL construction prefixes checked and retryable so partial failure cannot lose or replay resource ownership.

Co-authored-by: Codex <codex@openai.com>

src/AcDream.App/Rendering/BindlessTexturePair.cs

@@ -0,0 +1,94 @@
+namespace AcDream.App.Rendering;
+
+/// <summary>
+/// Owns the two independent residency edges used by TerrainAtlas. Acquisition
+/// and release publish each successful edge immediately, so a partial failure
+/// retries only work that is still pending.
+/// </summary>
+internal sealed class BindlessTexturePair(
+    uint firstTexture,
+    uint secondTexture,
+    Func<uint, ulong> acquire,
+    Action<ulong> release)
+{
+    private ulong _firstHandle;
+    private ulong _secondHandle;
+    private bool _firstResident;
+    private bool _secondResident;
+
+    public bool IsFullyResident => _firstResident && _secondResident;
+    public bool HasAnyResident => _firstResident || _secondResident;
+
+    public (ulong First, ulong Second) Acquire()
+    {
+        if (!_firstResident)
+        {
+            _firstHandle = acquire(firstTexture);
+            _firstResident = true;
+        }
+
+        if (!_secondResident)
+        {
+            try
+            {
+                _secondHandle = acquire(secondTexture);
+                _secondResident = true;
+            }
+            catch (Exception acquisitionFailure)
+            {
+                try
+                {
+                    Release();
+                }
+                catch (Exception cleanupFailure)
+                {
+                    throw new AggregateException(
+                        "Second bindless texture acquisition failed and the resident prefix did not cleanly roll back.",
+                        acquisitionFailure,
+                        cleanupFailure);
+                }
+
+                throw;
+            }
+        }
+
+        return (_firstHandle, _secondHandle);
+    }
+
+    public void Release()
+    {
+        List<Exception>? failures = null;
+        if (_firstResident)
+        {
+            try
+            {
+                release(_firstHandle);
+                _firstResident = false;
+                _firstHandle = 0;
+            }
+            catch (Exception failure)
+            {
+                (failures ??= []).Add(failure);
+            }
+        }
+
+        if (_secondResident)
+        {
+            try
+            {
+                release(_secondHandle);
+                _secondResident = false;
+                _secondHandle = 0;
+            }
+            catch (Exception failure)
+            {
+                (failures ??= []).Add(failure);
+            }
+        }
+
+        if (failures is not null)
+            throw new AggregateException(
+                "One or more bindless texture handles could not be made non-resident.",
+                failures);
+    }
+}