Fix build issues: csproj references, Unity modules, Harmony calls

- Fixed csproj to reference all Unity modules (Core, Audio, IMG, Input, TextRendering, UI)
- Fixed AudioMixerGUI namespace conflicts (GUI.Window vs UnityEngine.GUI.Window)
- Fixed Harmony UnpatchAll -> UnpatchSelf
- Removed duplicate AssemblyInfo.cs
- Build now succeeds and DLL deployed to BepInEx/plugins

src/HomuraHimeAudioMod/Build.ps1

@@ -9,7 +9,7 @@ param(
 
 $ErrorActionPreference = "Stop"
 
-$ProjectDir = Split-Path -Parent $PSScriptRoot
+$ProjectDir = $PSScriptRoot
 $ProjectFile = Join-Path $ProjectDir "HomuraHimeAudioMod.csproj"
 $DefaultOutput = Join-Path $ProjectDir "bin\$Configuration\net48"