feat(voice): run pipeline eyes-free (STT -> Brain -> TTS), defer screen share

Make source/vision optional so the conversation loop runs with no screen
capture. Add Settings.voice() preset and `python -m wsai --voice` demo.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

wsai/__main__.py

@@ -1,6 +1,7 @@
 """Entry point.
 
     python -m wsai              # mock pipeline (no deps, no keys) — runs a demo
+    python -m wsai --voice      # eyes-free voice loop demo (STT -> Brain -> TTS)
     python -m wsai --live       # capture this screen + Claude eyes/brain
     python -m wsai --env        # build from WSAI_* environment variables
 
@@ -25,7 +26,8 @@ async def _run(settings: Settings, demo: bool) -> None:
         from .pipeline import Pipeline
 
         pipe = build(settings)
-        pipe.source = MockFrameSource(interval=0.3, limit=4)
+        if pipe.source is not None:  # keep eyes-free configs eyes-free
+            pipe.source = MockFrameSource(interval=0.3, limit=4)
         if pipe.stt is not None:
             pipe.stt = MockSTT(interval=0.4)
         await pipe.run()
@@ -35,6 +37,7 @@ async def _run(settings: Settings, demo: bool) -> None:
 
 def main() -> None:
     ap = argparse.ArgumentParser(prog="wsai")
+    ap.add_argument("--voice", action="store_true", help="eyes-free voice loop (STT -> Brain -> TTS)")
     ap.add_argument("--live", action="store_true", help="capture screen + Claude backends")
     ap.add_argument("--env", action="store_true", help="build from WSAI_* env vars")
     ap.add_argument("-v", "--verbose", action="store_true")
@@ -45,7 +48,9 @@ def main() -> None:
         format="%(levelname)s %(name)s: %(message)s",
     )
 
-    if args.live:
+    if args.voice:
+        settings, demo = Settings.voice(), True
+    elif args.live:
         settings, demo = Settings.live(), False
     elif args.env:
         settings, demo = Settings.from_env(), False