wip(L16, side branch): disk terrain cache design + headless Linux prototype

Exact lossless zlib tile records (keyed on world/season/recipe/plan/evaluator/options/tile),
pristine cache plus ordered edits, server never trusts client caches, corruption/stale rejection,
atomic writes, 2 GB cap. Loaded tiles match regenerated hashes (L1 view, 24 m crossing).
NOT for assembler/world yet: the shared StreamBenchmarkPipeline.h includes Linux-only headers
(unistd/fcntl/zlib), which would break the Windows viewer build.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01CSFYgsdW8ejZSyiMf4qRSX

Standalone/BuildLinux.sh

@@ -118,7 +118,7 @@ PIDS=()
 CORE_LIBRARY="$BUILD_DIR/libVoxelForgeCore.a"
 "$(command -v ar)" rcs "$CORE_LIBRARY" "${CORE_OBJECTS[@]}"
 OUTPUT="$BIN_DIR/VoxelForgeCoreHeadless-$VARIANT"
-"$COMPILER" -pthread "${LEGACY_OBJECTS[@]}" "$CORE_LIBRARY" -o "$OUTPUT"
+"$COMPILER" -pthread "${LEGACY_OBJECTS[@]}" "$CORE_LIBRARY" -lz -o "$OUTPUT"
 CAPTURE_OUTPUT="$BIN_DIR/VoxelForgeOffscreenCapture-$VARIANT"
 "$COMPILER" -std=c++20 -O2 -fno-fast-math -pthread \
     "$ROOT/Source/LinuxOffscreenCapture.cpp" -o "$CAPTURE_OUTPUT" \