Fix review findings and Windows setup issues found in testing

- Run the server with -X utf8: the bundled Windows Python ignores PYTHON* variables.
- Quote every argument in Windows terminal commands, so cmd metacharacters are literal.
- frame_connect: accept HOST:PORT, validate input, retry the config swap while
  Windows' ssh.exe holds ~/.ssh/config locked, and don't apply 0o700 on Windows.
- Never use rsync on Windows; unbounded stream queue; validate FRAME_ALIAS;
  more Linux terminals; bundle the window icon; docs and wording fixes.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

app/package.json

@@ -27,7 +27,8 @@
     },
     "files": [
       "main.js",
-      "package.json"
+      "package.json",
+      "build/icon.png"
     ],
     "extraResources": [
       {