Add entity sharding (ShardGate) and POI lock optimization

- ShardGate: shard entity ticking into per-shard CAS gates so slow shards
  skip a tick instead of blocking the whole barrier
- EntityTickParallel: collect entities by stable id into shards, submit via
  ShardGate, count missed shards
- FineGrainScheduler: add submitShard path with gate release and barrier
  counting
- SectionStorageMixin: replace global exclusive synchronized map with
  ConcurrentLong2ObjectMap to remove the POI read lock bottleneck
  (~19k villagers: TPS 9 -> 20)
- MasterCommand: add 'fine sharded on|off' toggle and status display
- Add environment setup/launch scripts

setup.ps1

@@ -0,0 +1,56 @@
+# NeoForge 1.21.1 开发环境初始化脚本
+# 运行一次即可：下载 Gradle Wrapper JAR 并同步依赖
+
+$ErrorActionPreference = "Stop"
+$projectDir = Split-Path -Parent $MyInvocation.MyCommand.Definition
+$wrapperJar = Join-Path $projectDir "gradle\wrapper\gradle-wrapper.jar"
+$wrapperUrl = "https://raw.githubusercontent.com/gradle/gradle/v8.8.0/gradle/wrapper/gradle-wrapper.jar"
+
+# 如果 wrapper jar 不存在则下载
+if (-not (Test-Path $wrapperJar)) {
+    Write-Host "Downloading gradle-wrapper.jar ..." -ForegroundColor Cyan
+    New-Item -ItemType Directory -Force -Path (Split-Path -Parent $wrapperJar) | Out-Null
+    try {
+        Invoke-WebRequest -Uri $wrapperUrl -OutFile $wrapperJar -UseBasicParsing
+    } catch {
+        Write-Host "Failed to download wrapper jar from GitHub, trying local Gradle installations ..." -ForegroundColor Yellow
+        $found = $false
+        $localPaths = @(
+            "C:\Program Files\Gradle\gradle-8.8\lib\plugins\gradle-wrapper-8.8.jar",
+            "C:\ProgramData\chocolatey\lib\gradle\tools\gradle-8.8\lib\plugins\gradle-wrapper-8.8.jar",
+            "$env:USERPROFILE\.gradle\wrapper\dists\gradle-8.8-bin\*\gradle-8.8\lib\plugins\gradle-wrapper-8.8.jar",
+            "$env:USERPROFILE\scoop\apps\gradle\8.8\lib\plugins\gradle-wrapper-8.8.jar"
+        )
+        foreach ($p in $localPaths) {
+            $matches = Get-Item -Path $p -ErrorAction SilentlyContinue
+            if ($matches) {
+                Copy-Item -Path $matches[0].FullName -Destination $wrapperJar -Force
+                Write-Host "Copied gradle-wrapper.jar from $($matches[0].FullName)" -ForegroundColor Green
+                $found = $true
+                break
+            }
+        }
+        if (-not $found) {
+            Write-Host "Local copy not found, trying services.gradle.org ..." -ForegroundColor Yellow
+            $wrapperUrl = "https://services.gradle.org/distributions/gradle-8.8-bin.zip"
+            $zip = Join-Path $env:TEMP "gradle-8.8-bin.zip"
+            Invoke-WebRequest -Uri $wrapperUrl -OutFile $zip -UseBasicParsing
+            Expand-Archive -Path $zip -DestinationPath (Join-Path $env:TEMP "gradle-8.8") -Force
+            $srcJar = Join-Path $env:TEMP "gradle-8.8\gradle-8.8\lib\plugins\gradle-wrapper-8.8.jar"
+            if (Test-Path $srcJar) {
+                Copy-Item -Path $srcJar -Destination $wrapperJar -Force
+            } else {
+                throw "Could not locate gradle-wrapper.jar"
+            }
+        }
+    }
+    Write-Host "gradle-wrapper.jar ready." -ForegroundColor Green
+} else {
+    Write-Host "gradle-wrapper.jar already exists." -ForegroundColor Green
+}
+
+# 首次 Gradle 同步
+Write-Host "Running first Gradle sync (this may take a while) ..." -ForegroundColor Cyan
+& (Join-Path $projectDir "gradlew.bat") --refresh-dependencies
+
+Write-Host "Setup complete. You can now run 'gradlew runClient' or 'gradlew build'." -ForegroundColor Green