build: align RootNamespace with HellionChat post-rename

Updates the project root namespace and replaces the historical comment
about cherry-pick compatibility — that compatibility was the rationale
for keeping ChatTwo.* in source while AssemblyName was already
HellionChat. With v1.0.0 the standalone cut is complete and both
identifiers match.

Note: this commit also fixes the runtime MissingManifestResourceException
that the previous Task 6 commit caused — the embedded resource prefix
is derived from RootNamespace at build time, so Designer.cs string
arguments and the actual resource names only line up once both are set
to HellionChat.

ChatTwo/ChatTwo.csproj

@@ -6,13 +6,12 @@
              derives from. -->
         <Version>0.6.1</Version>
         <ImplicitUsings>enable</ImplicitUsings>
-        <!-- HellionChat fork: assembly is renamed so Dalamud uses
-             pluginConfigs/HellionChat instead of pluginConfigs/ChatTwo,
-             keeping our state independent from the upstream plugin.
-             Code namespace stays ChatTwo.* so upstream cherry-picks
-             apply cleanly. -->
+        <!-- v1.0.0 standalone cut — both AssemblyName and RootNamespace
+             are HellionChat. The plugin no longer maintains source-level
+             cherry-pick compatibility with upstream Infiziert90/ChatTwo;
+             upstream changes are integrated manually if at all. -->
         <AssemblyName>HellionChat</AssemblyName>
-        <RootNamespace>ChatTwo</RootNamespace>
+        <RootNamespace>HellionChat</RootNamespace>
     </PropertyGroup>
 
     <ItemGroup>