v0.2.0: splats, copy/paste, faster homes, seat facing, and a full bug sweep

Frame Studio
- Gaussian splats (PLY, SPZ v2-v4), PLY vertex colours, panorama skies
- Copy, cut, paste and duplicate for objects, splats and world items
- Walkable-area rebake moved off the UI thread; viewport one frame sooner;
  refresh-locked pacing (FS_PACE=timer for the old one)
- Fixed: bundle thumbnail use-after-free crash, auto-save deleting
  environments, saves into scratch copies, edits lost on non-ASCII paths,
  unopenable manifests with inf/nan, bundle save data loss, opening a home
  marking it changed, gizmo NaN, long paths, many malformed-file crashes
- Updater verifies sha256, journals the swap and never leaves the exe missing

Frame Home
- Seats turn you to face their way
- Draw batching (Hand Tutorials up to ~20% less GPU time), cut-out EQUAL pass,
  late head-pose read before submit
- Proper queue-family hand-over to the compositor layer; layer descriptor
  generations and seqlocked slots; structural SPIR-V check
- Fixed: hangs/crashes on damaged .fenv files and shaders, render-pass
  validation error, sync hazard in the foveation smoothing pass, unverified
  update downloads, half-done installs

Tests: tests_loco/env_share/spv_check wired into CMake (FRAME_TESTS) and CI.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VsaXGU27gsrXjDoFtyFJP9

third_party/spirv-tools/source/opt/dataflow.cpp

@@ -0,0 +1,90 @@
+// Copyright (c) 2021 Google LLC.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "source/opt/dataflow.h"
+
+#include <cstdint>
+
+namespace spvtools {
+namespace opt {
+
+bool DataFlowAnalysis::Enqueue(Instruction* inst) {
+  bool& is_enqueued = on_worklist_[inst];
+  if (is_enqueued) return false;
+  is_enqueued = true;
+  worklist_.push(inst);
+  return true;
+}
+
+DataFlowAnalysis::VisitResult DataFlowAnalysis::RunOnce(
+    Function* function, bool is_first_iteration) {
+  InitializeWorklist(function, is_first_iteration);
+  VisitResult ret = VisitResult::kResultFixed;
+  while (!worklist_.empty()) {
+    Instruction* top = worklist_.front();
+    worklist_.pop();
+    on_worklist_[top] = false;
+    VisitResult result = Visit(top);
+    if (result == VisitResult::kResultChanged) {
+      EnqueueSuccessors(top);
+      ret = VisitResult::kResultChanged;
+    }
+  }
+  return ret;
+}
+
+void DataFlowAnalysis::Run(Function* function) {
+  VisitResult result = RunOnce(function, true);
+  while (result == VisitResult::kResultChanged) {
+    result = RunOnce(function, false);
+  }
+}
+
+void ForwardDataFlowAnalysis::InitializeWorklist(Function* function,
+                                                 bool /*is_first_iteration*/) {
+  context().cfg()->ForEachBlockInReversePostOrder(
+      function->entry().get(), [this](BasicBlock* bb) {
+        if (label_position_ == LabelPosition::kLabelsOnly) {
+          Enqueue(bb->GetLabelInst());
+          return;
+        }
+        if (label_position_ == LabelPosition::kLabelsAtBeginning) {
+          Enqueue(bb->GetLabelInst());
+        }
+        for (Instruction& inst : *bb) {
+          Enqueue(&inst);
+        }
+        if (label_position_ == LabelPosition::kLabelsAtEnd) {
+          Enqueue(bb->GetLabelInst());
+        }
+      });
+}
+
+void ForwardDataFlowAnalysis::EnqueueUsers(Instruction* inst) {
+  context().get_def_use_mgr()->ForEachUser(
+      inst, [this](Instruction* user) { Enqueue(user); });
+}
+
+void ForwardDataFlowAnalysis::EnqueueBlockSuccessors(Instruction* inst) {
+  if (inst->opcode() != spv::Op::OpLabel) return;
+  context()
+      .cfg()
+      ->block(inst->result_id())
+      ->ForEachSuccessorLabel([this](uint32_t* label) {
+        Enqueue(context().cfg()->block(*label)->GetLabelInst());
+      });
+}
+
+}  // namespace opt
+}  // namespace spvtools