[Fix] (MG_Backend/DirectGLES, MG_State, Docs): CopyImageSubData held a registry reference across a re-entrant sync; retarget container rationales at the new erase contract

MobileGL/MG_State/GLState/BufferState/BufferState.cpp

@@ -67,9 +67,13 @@ namespace MobileGL::MG_State::GLState {
                         }
                     }
                 }
-                // Key-based erase skips FastSTL's successor-iterator scan, which is
-                // pure overhead here and dominates delete-heavy frames.
-                m_bufferObjects.erase(index);
+                // Erase through the iterator already in hand: erase(key) would repeat the
+                // find() from line 55, and the successor scan that once made key-based
+                // erase the cheaper of the two no longer happens here - erase(iterator)
+                // hands back an unconverted proxy, and the scan is what converting it
+                // would cost. The unbind loops above touch only the binding arrays, so
+                // `it` is still live.
+                m_bufferObjects.erase(it);
             }
             m_indexGenerator.Delete(index);
         }

MobileGL/MG_State/GLState/ProgramState/ShaderCompileAdoptionMap.cpp

@@ -70,9 +70,10 @@ namespace MobileGL::MG_State::GLState {
     void ShaderCompileAdoptionMap::SweepIfCrowded() {
         if (m_entries.size() < m_sweepThreshold) return;
 
-        // Collect first, erase after: FastSTL::unordered_map is open-addressed, so erasing
-        // through an iterator that the same loop is still advancing is not worth reasoning
-        // about on a path this cold.
+        // Collect first, erase after: the map is open-addressed and erases by shifting the
+        // rest of the probe cluster into the hole, so an erase moves entries other than the
+        // erased one. Copying the keys out sidesteps that entirely, and this path is cold
+        // enough that the extra vector is not worth reasoning about the alternative.
         Vector<ShaderSourceKey> dead;
         for (const auto& entry : m_entries) {
             const SharedPtr<ShaderCompileTask> node = entry.second.lock();