Implement playable Mac client and rendering validation

test/rendering/particle-leak/.gitignore

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+.godot/

test/rendering/particle-leak/README.md

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+# Particle shader lifetime reproducer
+
+Independent Godot project: no game assets, autoloads, GDExtension, network,
+EffectPlayer, or particles emitter. Eight short-lived ParticleProcessMaterials
+cycle through three emission shapes. Weak references must all be dead before
+exit; a RenderingServer synchronization also runs before quitting.
+
+Export this project with the installed macOS template using `--export-release`
+and `--export-debug` into separate directories under the repository's `build/`.
+Run each exported executable and preserve both stdout and stderr until process
+exit. A run is clean only if `ISOLATED_PARTICLE_EXIT alive=0` is present and no
+shader/RID error follows. The success marker alone is not a clean-exit verdict.
+
+2026-09-10, Godot 4.7.1 official, Apple M4/Metal:
+
+- Release: zero surviving materials, three ParticlesShaderRD/Shader RID leaks.
+- Debug: zero surviving materials, no shader/RID leak.
+
+Logs: `build/rendering/particle-isolated-release.log` and
+`build/rendering/particle-isolated-debug.log`. Path overrides (`--main-pack`,
+external `--script`) are not supported by the installed release template;
+export a standalone app instead. This project contains no copyrighted artwork
+and may be used as a minimal upstream reproduction if separately authorized.
+
+2026-09-11: an unmodified same-revision arm64 release build using
+`debug_symbols=yes optimize=speed lto=none vulkan=no` exits cleanly in this
+project and in two complete game package checks. Rebuild it with
+`bash script/build_macos_release_engine.sh arm64` from the repository root.
+This is a verified alternative build path, not proof of a specific compiler
+bug or a source fix to the installed official template. Intel and Vulkan are
+outside this result.

test/rendering/particle-leak/export_presets.cfg

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+[preset.0]
+name="macOS"
+platform="macOS"
+runnable=true
+export_filter="all_resources"
+include_filter=""
+exclude_filter=""
+[preset.0.options]
+application/bundle_identifier="org.metin2.particleprobe"

test/rendering/particle-leak/main.gd

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+extends Node
+var refs: Array[WeakRef] = []
+func _ready() -> void: call_deferred("run")
+func run() -> void:
+	for i in 8: create_material(i)
+	for i in 10: await get_tree().process_frame
+	RenderingServer.force_sync()
+	var alive := 0
+	for reference in refs:
+		if reference.get_ref() != null: alive += 1
+	print("ISOLATED_PARTICLE_EXIT alive=", alive)
+	get_tree().quit(1 if alive else 0)
+func create_material(index: int) -> void:
+	var material := ParticleProcessMaterial.new()
+	material.emission_shape = index % 3
+	material.get_rid()
+	refs.append(weakref(material))

test/rendering/particle-leak/main.gd.uid

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+uid://b3vjaypwq6yx6

test/rendering/particle-leak/main.tscn

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+[gd_scene load_steps=2 format=3]
+[ext_resource type="Script" path="res://main.gd" id="1"]
+[node name="Probe" type="Node"]
+script = ExtResource("1")

test/rendering/particle-leak/project.godot

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+config_version=5
+[application]
+config/name="Particle lifetime isolation"
+run/main_scene="res://main.tscn"
+[display]
+window/size/viewport_width=320
+window/size/viewport_height=240
+[rendering]
+textures/vram_compression/import_etc2_astc=true