v1.16 — Remove PowerShell edition, restore flat project structure

PowerShell version removed — will use OV code signing certificate instead.
Files moved back from src/ to project root.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

InstaSoftOfficeTool.csproj

@@ -0,0 +1,27 @@
+<Project Sdk="Microsoft.NET.Sdk">
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net48</TargetFramework>
+    <UseWPF>true</UseWPF>
+    <RootNamespace>InstaSoftOfficeTool</RootNamespace>
+    <AssemblyName>InstaSoftOfficeTool</AssemblyName>
+    <ApplicationIcon>Resources\app.ico</ApplicationIcon>
+    <Company>InstaSoft Zrt.</Company>
+    <Product>InstaSoft Office Tool</Product>
+    <Copyright>Copyright (c) InstaSoft Zrt. 2026</Copyright>
+    <Version>1.1.5</Version>
+    <AssemblyVersion>1.1.5.0</AssemblyVersion>
+    <FileVersion>1.1.5.0</FileVersion>
+    <ApplicationManifest>app.manifest</ApplicationManifest>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.NETFramework.ReferenceAssemblies" Version="1.0.3" PrivateAssets="all" />
+    <Reference Include="System.Net.Http" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <Resource Include="Resources\app.ico" />
+  </ItemGroup>
+</Project>