Use 16 KB-aligned ppy.Veldrid.SPIRV fork build via local-packages

The previous pin to `1.0.15-gb66ebf81d2` was the ppy.org build, whose
`runtimes/android-arm64/native/libveldrid-spirv.so` is 4 KB-aligned and
triggers the "Android 16 will require 16 KB page sizes" warning when
packaging the APK.

The winnerspiros fork build `1.0.15-gb268bf39ea` (the version
ppy.osu.Framework 2026.421.1 was originally compiled against) is
properly 16 KB-aligned, but it lives only as a release asset on
`winnerspiros/veldrid-spirv` (release `1.0`) — it is not on nuget.org or
GitHub Packages, so NuGet was silently falling back to the ppy build.

Vendor the correct nupkg under `local-packages/` (with a `.gitignore`
exception so it's tracked despite the root `*.nupkg` rule) and re-add
the `local-packages` source to `NuGet.Config`. Re-pin the SPIRV
reference in `osu.Game.csproj` to the fork version. The pin flows
transitively to every project via existing ProjectReferences.

Verified: ELF PT_LOAD segments in the vendored .so are aligned to
0x4000 (16 KB).

Agent-Logs-Url: https://github.com/winnerspiros/osu/sessions/dd5477f1-781f-483e-a69a-835fd8edac93

Co-authored-by: winnerspiros <1675249+winnerspiros@users.noreply.github.com>

Author: Copilot

NuGet.Config

@@ -4,6 +4,8 @@
     <clear />
     <!-- winnerspiros/osu-framework fork NuGet packages (published to GitHub Packages) -->
     <add key="winnerspiros-github" value="https://nuget.pkg.github.com/winnerspiros/index.json" />
+    <!-- Vendored .nupkgs that aren't on any feed (see local-packages/README.md). -->
+    <add key="local-packages" value="./local-packages" />
     <add key="nuget.org" value="https://api.nuget.org/v3/index.json" />
   </packageSources>
 </configuration>

local-packages/.gitignore

@@ -0,0 +1,2 @@
+# Override root *.nupkg exclusion so vendored fork packages can be committed here.
+!*.nupkg

local-packages/README.md

@@ -0,0 +1,24 @@
+# `local-packages/` — vendored NuGet packages
+
+This folder hosts pre-built `.nupkg` files for fork dependencies that are not
+published to a public NuGet feed and that GitHub Packages cannot host (e.g.
+release-asset-only artifacts).
+
+It is wired up as a NuGet source in the repo-root `NuGet.Config`:
+
+```xml
+<add key="local-packages" value="./local-packages" />
+```
+
+## Current contents
+
+| Package                         | Version                | Why vendored |
+|---------------------------------|------------------------|--------------|
+| `ppy.Veldrid.SPIRV`             | `1.0.15-gb268bf39ea`   | This fork build (from <https://github.com/winnerspiros/veldrid-spirv/releases/tag/1.0>) ships `runtimes/android-arm64/native/libveldrid-spirv.so` aligned to **16 KB pages**, which is required for Android 16+. The version published on nuget.org (`1.0.15-gb66ebf81d2`) is 4 KB-aligned and triggers a build warning when packaging the APK. The version is referenced by `ppy.osu.Framework 2026.421.1` and re-pinned explicitly in `osu.Game/osu.Game.csproj` so resolution is deterministic. |
+
+## Updating
+
+When the fork rebuilds the package, drop the new `.nupkg` here, bump the
+`Version` in `osu.Game/osu.Game.csproj` (and any direct framework reference if
+the dep target version changes), and delete the old `.nupkg` so the folder
+stays small.

local-packages/ppy.Veldrid.SPIRV.1.0.15-gb268bf39ea.nupkg

@@ -40,14 +40,15 @@
     <PackageReference Include="Realm" Version="20.1.0" />
     <PackageReference Include="ppy.osu.Framework" Version="2026.421.1" />
     <!--
-      Explicitly pin `ppy.Veldrid.SPIRV` to a published version. `ppy.osu.Framework` 2026.421.1 was
-      built against `ppy.Veldrid.SPIRV 1.0.15-gb268bf39ea`, which is a winnerspiros fork build that
-      was never published to a public NuGet feed. Without this explicit reference NuGet falls back
-      to the nearest available version on nuget.org and emits NU1603, which `-warnaserror` (used by
-      both the `Code Quality` and `Test` CI jobs) turns into build errors. The published version
-      below is binary-compatible with what the framework expects.
+      Explicitly pin `ppy.Veldrid.SPIRV` to the winnerspiros fork build that
+      `ppy.osu.Framework 2026.421.1` was compiled against. This version is the only
+      one whose `runtimes/android-arm64/native/libveldrid-spirv.so` is aligned to 16 KB
+      pages (required by Android 16+). It lives only as a release asset on
+      <https://github.com/winnerspiros/veldrid-spirv/releases/tag/1.0> and is vendored
+      under `local-packages/` (see `local-packages/README.md`). Without this pin NuGet
+      would silently fall back to the 4 KB-aligned nuget.org build and emit NU1903.
     -->
-    <PackageReference Include="ppy.Veldrid.SPIRV" Version="1.0.15-gb66ebf81d2" />
+    <PackageReference Include="ppy.Veldrid.SPIRV" Version="1.0.15-gb268bf39ea" />
     <PackageReference Include="ppy.osu.Game.Resources" Version="2026.420.0" />
     <PackageReference Include="Sentry" Version="6.2.0" />
     <!-- Held back due to 0.34.0 failing AOT compilation on ZstdSharp.dll dependency. -->