Test project: UT-001..011 for JR-016 and JR-022

The register defined 46 requirements and zero tests, so every Done in it rested
on inspection. This adds the T1 tier: an xUnit project in the solution,
covering the two units whose logic is pure enough to test without a Jellyfin
host.

JR-022 (UT-001..006) covers the cases where removal could reach too far --
another plugin's injection, and an unmarked look-alike script tag -- because
index.html is a file JRay shares. UT-001 pins the trailing newline to the tag,
without which every install cycle leaves another blank line behind.

JR-016 (UT-007..011) covers specificity resolution, including the prioritised
series inside an ignored genre that motivated the rule, and a Series rule
valued Guid.Empty, which would otherwise swallow every movie in the library.

RemoveInjection is reached through InternalsVisibleTo rather than being made
public: it is factored out for testability, not part of the surface.

The suite BUILDS but does not RUN here. Jellyfin.Controller framework-
references Microsoft.AspNetCore.App, so the test host demands it even for pure
logic, and this machine has no ASP.NET Core runtime at any version --
RollForward cannot substitute for a framework that is absent entirely. Fix is
to install aspnet-runtime, which the CI image needs for the same reason.

So every UT here is recorded as Written, not Passing, and no requirement is
promoted to Done on their strength. A test whose result nobody has seen is not
evidence.

TRACES: UT-001, UT-002, UT-003, UT-004, UT-005, UT-006 | JR-022
TRACES: UT-007, UT-008, UT-009, UT-010, UT-011 | JR-016

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

Jellyfin.Plugin.JRay/Jellyfin.Plugin.JRay.csproj

@@ -25,6 +25,15 @@
     <PackageReference Include="SmartAnalyzers.MultithreadingAnalyzer" Version="1.1.31" PrivateAssets="All" />
   </ItemGroup>
 
+  <ItemGroup>
+    <!-- Lets the test project reach internals such as
+         WebClientPatchService.RemoveInjection, which is factored out precisely
+         so the removal logic is testable without touching a filesystem. -->
+    <AssemblyAttribute Include="System.Runtime.CompilerServices.InternalsVisibleToAttribute">
+      <_Parameter1>Jellyfin.Plugin.JRay.Tests</_Parameter1>
+    </AssemblyAttribute>
+  </ItemGroup>
+
   <ItemGroup>
     <None Remove="Configuration\configPage.html" />
     <EmbeddedResource Include="Configuration\configPage.html" />