v0.1: Robovoice — PTT re-voicing app

WinForms tray app that captures text (from file or direct input) and
synthesizes speech via libpiper (Piper TTS), outputting to any audio
device (VB-CABLE for virtual mic routing).

Features:
- Global PTT hotkey (configurable F1-F12) via WH_KEYBOARD_LL
- Text file sequential reader (line-by-line on each PTT cycle)
- Direct text input with Speak button
- Voice manager: browse 147-voice Piper catalogue, download, remove
- libpiper P/Invoke wrapper with UTF-8 marshaling, streaming chunks
- BufferedWaveProvider streaming playback with trailing silence flush
- Sentence terminator auto-append (fixes espeak-ng final-word drop)
- Tray icon with minimize-to-tray

Architecture:
- Robovoice.Core: ITtsEngine, ISttSource interfaces, voice catalogue
- Robovoice.Tts.LibPiper: P/Invoke wrapper for libpiper.dll
- Robovoice.Stt.File: text file STT source (testing without mic server)
- Robovoice.Stt.Udp: UDP client stub (for future Linux mic server)
- Robovoice.App: WinForms UI, orchestrator, PTT hotkey, audio output

Robovoice.App/Robovoice.App.csproj

@@ -0,0 +1,22 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <ItemGroup>
+    <ProjectReference Include="..\Robovoice.Core\Robovoice.Core.csproj" />
+    <ProjectReference Include="..\Robovoice.Tts.LibPiper\Robovoice.Tts.LibPiper.csproj" />
+    <ProjectReference Include="..\Robovoice.Stt.File\Robovoice.Stt.File.csproj" />
+    <ProjectReference Include="..\Robovoice.Stt.Udp\Robovoice.Stt.Udp.csproj" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <PackageReference Include="NAudio" Version="2.3.0" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <OutputType>WinExe</OutputType>
+    <TargetFramework>net10.0-windows</TargetFramework>
+    <Nullable>enable</Nullable>
+    <UseWindowsForms>true</UseWindowsForms>
+    <ImplicitUsings>enable</ImplicitUsings>
+  </PropertyGroup>
+
+</Project>