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.Stt.File/FileSttSource.cs

@@ -0,0 +1,83 @@
+using Robovoice.Core;
+
+namespace Robovoice.Stt.File;
+
+public sealed class FileSttSource : ISttSource
+{
+    private readonly object _lock = new();
+    private string[] _lines = Array.Empty<string>();
+    private int _currentIndex;
+    private bool _disposed;
+
+    public event TranscriptEventHandler? TranscriptReceived;
+
+    public string FilePath { get; set; } = string.Empty;
+    public int LineCount { get; private set; }
+    public int CurrentIndex => _currentIndex;
+
+    public void LoadFile(string path)
+    {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+        FilePath = path;
+        _lines = System.IO.File.ReadAllLines(path);
+        LineCount = _lines.Length;
+        _currentIndex = 0;
+    }
+
+    public string? GetPendingLine()
+    {
+        lock (_lock)
+        {
+            if (_lines.Length == 0) return null;
+            int idx = _currentIndex % _lines.Length;
+            return _lines[idx];
+        }
+    }
+
+    public void EmitNext()
+    {
+        ObjectDisposedException.ThrowIf(_disposed, this);
+        string? line = null;
+        lock (_lock)
+        {
+            if (_lines.Length > 0)
+            {
+                int idx = _currentIndex % _lines.Length;
+                line = _lines[idx];
+                _currentIndex++;
+            }
+        }
+
+        if (!string.IsNullOrWhiteSpace(line))
+        {
+            TranscriptReceived?.Invoke(this, new TranscriptEventArgs
+            {
+                Message = new TranscriptMessage(TranscriptType.Final, line!),
+            });
+        }
+    }
+
+    public void Reset()
+    {
+        lock (_lock)
+        {
+            _currentIndex = 0;
+        }
+    }
+
+    public Task StartAsync(CancellationToken ct = default)
+    {
+        return Task.CompletedTask;
+    }
+
+    public Task StopAsync(CancellationToken ct = default)
+    {
+        return Task.CompletedTask;
+    }
+
+    public ValueTask DisposeAsync()
+    {
+        _disposed = true;
+        return ValueTask.CompletedTask;
+    }
+}

Robovoice.Stt.File/Robovoice.Stt.File.csproj

@@ -0,0 +1,13 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <ItemGroup>
+    <ProjectReference Include="..\Robovoice.Core\Robovoice.Core.csproj" />
+  </ItemGroup>
+
+  <PropertyGroup>
+    <TargetFramework>net10.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>