feat(voice-client): PySide6 desktop client and Windows build scripts

Add voice_confirmation_client (poll, TTS MP3 playback, mic WAV resolve),
PyInstaller spec, start/build helpers, and API unit tests.

Pending manual testing: end-to-end on OR workstations and packaged exe.

Made-with: Cursor

voice_client.spec

@@ -0,0 +1,56 @@
+# PyInstaller spec for the voice confirmation desktop client.
+# Build on the target OS (Windows / macOS / Linux).
+# Usage: uv run --group voice-client-build pyinstaller voice_client.spec
+
+from PyInstaller.utils.hooks import collect_all
+
+datas, binaries, hiddenimports = collect_all("PySide6")
+
+block_cipher = None
+
+a = Analysis(
+    ["voice_confirmation_client/__main__.py"],
+    pathex=[],
+    binaries=binaries,
+    datas=datas,
+    hiddenimports=hiddenimports + ["sounddevice", "numpy"],
+    hookspath=[],
+    hooksconfig={},
+    runtime_hooks=[],
+    excludes=[],
+    win_no_prefer_redirects=False,
+    win_private_assemblies=False,
+    cipher=block_cipher,
+    noarchive=False,
+)
+
+pyz = PYZ(a.pure, a.zipped_data, cipher=block_cipher)
+
+exe = EXE(
+    pyz,
+    a.scripts,
+    [],
+    exclude_binaries=True,
+    name="voice-confirmation-client",
+    debug=False,
+    bootloader_ignore_signals=False,
+    strip=False,
+    upx=False,
+    console=False,
+    disable_windowed_traceback=False,
+    argv_emulation=False,
+    target_arch=None,
+    codesign_identity=None,
+    entitlements_file=None,
+)
+
+coll = COLLECT(
+    exe,
+    a.binaries,
+    a.zipfiles,
+    a.datas,
+    strip=False,
+    upx=False,
+    upx_exclude=[],
+    name="voice-confirmation-client",
+)