Warmup-safe skill assignment, PerfLog header

- Treat null GameRules as "not ready" so skills are never assigned during
  warmup right after plugin load/hot-reload (SetSkill + RoundStart)
- PerfLog writes a header line on first measurement so the perf file
  appears immediately when PerfMode is active

jRandomSkills - SRC Files/jRandomSkills.csproj

@@ -71,7 +71,9 @@
         <Message Text="Copying compiled DLL from $(SourceDLL) to $(ServerDLL)" Importance="High" />
         <ItemGroup>
             <CompiledDLL Include="$(SourceDLL)\jRandomSkills.dll" />
+            <CompiledDLL Include="$(SourceDLL)\jRandomSkills.pdb" />
             <CompiledDLL Include="$(SourceDLL)\WASDMenuAPI.dll" />
+            <CompiledDLL Include="$(SourceDLL)\WASDMenuAPI.pdb" />
 	        <CompiledDLL Include="$(SourceDLL)\MaxMind.Db.dll" />
 	        <CompiledDLL Include="$(SourceDLL)\Newtonsoft.Json.dll" />
         </ItemGroup>