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.

repo.json

@@ -26,10 +26,10 @@
     "DownloadLinkUpdate": "https://github.com/JonKazama-Hellion/HellionChat/releases/download/v0.6.1/latest.zip",
     "DownloadLinkTesting": "https://github.com/JonKazama-Hellion/HellionChat/releases/download/v0.6.1/latest.zip",
     "TestingAssemblyVersion": "0.6.1.0",
-    "IconUrl": "https://raw.githubusercontent.com/JonKazama-Hellion/HellionChat/main/ChatTwo/images/icon.png",
+    "IconUrl": "https://raw.githubusercontent.com/JonKazama-Hellion/HellionChat/main/HellionChat/images/icon.png",
     "ImageUrls": [
-      "https://raw.githubusercontent.com/JonKazama-Hellion/HellionChat/main/ChatTwo/images/chatWindow.png",
-      "https://raw.githubusercontent.com/JonKazama-Hellion/HellionChat/main/ChatTwo/images/withSimpleTweaks.png"
+      "https://raw.githubusercontent.com/JonKazama-Hellion/HellionChat/main/HellionChat/images/chatWindow.png",
+      "https://raw.githubusercontent.com/JonKazama-Hellion/HellionChat/main/HellionChat/images/withSimpleTweaks.png"
     ],
     "DownloadCount": 0,
     "IsHide": false,