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, 1 insertions, 1 deletions

diff --git a/packages/meshbay-node/tests/test_enrich_photo.py b/packages/meshbay-node/tests/test_enrich_photo.py
index 877a71d..7684f40 100644
--- a/packages/meshbay-node/tests/test_enrich_photo.py
+++ b/packages/meshbay-node/tests/test_enrich_photo.py
@@ -185,6 +185,6 @@ def test_gps_is_never_read_by_this_module():
     what this test is guarding against.
     """
     src = (Path(__file__).resolve().parents[1] / "src" / "meshbay_node"
-           / "indexer" / "enrich_photo.py").read_text()
+           / "indexer" / "enrich_photo.py").read_text(encoding="utf-8")
     for needle in ("GPSInfo", "GPSTAGS", "0x8825", "34853"):
         assert needle not in src, f"found {needle!r} — GPS extraction must never be added here"