build: rename repository folder ChatTwo to HellionChat

Repository folder, csproj, solution and all CI/build paths now use
the consolidated HellionChat name.

- ChatTwo/ → HellionChat/ (git mv preserves history with --follow)
- ChatTwo.csproj → HellionChat.csproj
- ChatTwo.sln → HellionChat.sln; obsolete Tests project entry removed
  (private/untracked sandbox)
- AssemblyInfo.cs InternalsVisibleTo for ChatTwo.Tests removed
  (file emptied; can be repopulated when actual tests land)
- repo.json and yaml image URLs updated (ChatTwo/images/ → HellionChat/images/)
- .github/workflows/{build,codeql,release}.yml csproj paths
- .github/dependabot.yml directory path

Functional behavior unchanged.

.github/workflows/build.yml

@@ -42,15 +42,15 @@ jobs:
           Expand-Archive -Force -Path dalamud.zip -DestinationPath $hooks
 
       - name: Restore
-        run: dotnet restore ChatTwo/ChatTwo.csproj
+        run: dotnet restore HellionChat/HellionChat.csproj
 
       - name: Build (Release)
-        run: dotnet build ChatTwo/ChatTwo.csproj --configuration Release --no-restore
+        run: dotnet build HellionChat/HellionChat.csproj --configuration Release --no-restore
 
       - name: Upload build output
         uses: actions/upload-artifact@v7
         with:
           name: HellionChat-build-${{ github.run_number }}
-          path: ChatTwo/bin/Release/**/HellionChat/**
+          path: HellionChat/bin/Release/**/HellionChat/**
           if-no-files-found: warn
           retention-days: 14