perf(network): consume IORingGroup 1.0.9 to drop the per-iteration 6 KiB memset (#2558)

## Problem

`IORingGroup`'s `WindowsManagedRIOGroup.DequeueRioCompletions` stackallocs `RIORESULT[256]` (6144 bytes) and runs **once per game-loop iteration** — `NetState.Slice` → `RingSocketManager.ProcessCompletions` → `PeekCompletions` → `DequeueRioCompletions`.

The 1.0.8 package was compiled with the `.locals init` IL flag set, so every one of those calls memset the full 6 KiB before `RIODequeueCompletion` overwrote the entries it actually filled.

An EventPipe profile of a near-idle shard (3 vCPU VPS, world saves off, one player logging in and moving around) put `System.Buffer.ZeroMemoryInternal` — called directly from `DequeueRioCompletions` — at **~2.8% of main-thread samples**, and it was the dominant frame in several 60–127 ms game-loop stalls.

## Why our existing attribute didn't cover it

`Projects/Server/Module.cs` and `Projects/UOContent/Module.cs` already declare `[module: SkipLocalsInit]`. That attribute is a **compile-time** directive: it clears the flag in the IL of the assembly being compiled, and does not cross assembly boundaries. It never applied to the package.

Verified by reading the shipped IL (`MethodBodyBlock.LocalVariablesInitialized`):

| Assembly | attribute | methods with `.locals init` |
|---|---|---|
| `Server.dll` | present | 0 of 5439 |
| `IORingGroup` 1.0.8 | **absent** | **158** |
| `IORingGroup` 1.0.9 | present | **0 of 389** |

## Testing

Built and tested against the locally-built 1.0.9 package (temporary local feed, not committed):

- `dotnet build -c Release` — **0 warnings, 0 errors**
- `Server.Tests` — **810 passed, 0 failed**
- `UOContent.Tests` — **637 passed, 0 failed**
- Confirmed the `IORingGroup.dll` deployed to `Distribution/` is the fixed build (0 of 389 methods zeroing)

Only the `<PackageReference>` version changes; no source changes on this side.

Projects/Server/Server.csproj

@@ -34,7 +34,7 @@
     </Target>
     <ItemGroup>
         <ProjectReference Include="..\Logger\Logger.csproj" />
-        <PackageReference Include="IORingGroup" Version="1.0.8" />
+        <PackageReference Include="IORingGroup" Version="1.0.9" />
         <PackageReference Include="CommunityToolkit.HighPerformance" Version="8.4.2" />
         <PackageReference Include="LibDeflate.Bindings" Version="1.0.3" />
         <PackageReference Include="System.IO.Hashing" Version="10.0.10" />