test(node): make the suite pass on Windows

- `.read_text()` on source files now `encoding="utf-8"` — cp1252 chokes on
  the em dashes / box-drawing chars those files contain.
- test node.toml templates embed paths via `Path.as_posix()`: a raw Windows
  path in a basic TOML string is a parse error (`\U`, `\a`, ... are escapes).
- new `test_platform.py` covers `meshbay_node.platform` by mocking
  `sys.platform` / `os.environ` — runs on both OSes.
- `skipif(sys.platform == "win32")`, in `conftest.needs_subprocess` and
  inline, for the documented gaps: ffmpeg/ffprobe via asyncio subprocess
  (the win32 selector loop, forced for aiortc, cannot spawn one), the
  systemd `reload`/`restart-daemon` delegation (Windows path is W3), the
  keystore `st_mode == 600` assertion (NTFS ignores mode bits), and the
  symlink-escape test (needs Developer Mode).

Windows: 781 passed, 25 skipped. No change on Linux.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

1 files changed, 2 insertions, 1 deletions

diff --git a/packages/meshbay-node/tests/test_stream_audio_transcode.py b/packages/meshbay-node/tests/test_stream_audio_transcode.py
index aaf1595..959cc91 100644
--- a/packages/meshbay-node/tests/test_stream_audio_transcode.py
+++ b/packages/meshbay-node/tests/test_stream_audio_transcode.py
@@ -28,12 +28,13 @@ from meshbay_common.webcrypto import chunk_key_aes, decrypt_chunk_aes
 from meshbay_node.indexer.group_index import GroupIndex
 from meshbay_node.transport.webrtc_server import WebRTCPeerSession, _probe_video
 
-from conftest import one_root
+from conftest import needs_subprocess, one_root
 
 _HAVE_FFMPEG = shutil.which("ffmpeg") and shutil.which("ffprobe")
 pytestmark = [
     pytest.mark.asyncio,
     pytest.mark.skipif(not _HAVE_FFMPEG, reason="ffmpeg/ffprobe not installed"),
+    needs_subprocess,
 ]