feat: Windows installer (W4) — one per-user NSIS package, client + node

`npm run dist:win` produces MeshBay-Setup-<version>.exe: the Electron client
and, beside it under resources/node-runtime/, the frozen meshbay-node daemon
(meshbay-common inside it). No hub. Per-user, no elevation — matches the W3
constraint that a logon-triggered scheduled task needs admin.

electron-builder / package.json
  build.win   nsis, build/icon.ico, extraResources -> node-runtime/
  build.nsis  oneClick:false perMachine:false allowElevation:false
              allowToChangeInstallationDirectory:true
  dist:win    -> packaging/win/build-win.ps1 (mirrors dist -> build-client.sh)

packaging/win/
  meshbay-node.spec + node-entry.py   PyInstaller freeze of
      meshbay_node.daemon:main. The awkward deps (aiortc, av, aioquic,
      pydantic_core, uvicorn, watchdog, guessit, blake3, tzdata) are pulled
      in whole with collect_all — that list is expected to grow when a frozen
      run raises ModuleNotFoundError.
  build-node-runtime.ps1   throwaway venv -> pip install -> PyInstaller ->
      packages/meshbay-client/node-runtime/ (gitignored)
  build-win.ps1            Node>=22 check, npm ci, Electron bump, sync-ui,
      node runtime, electron-builder --win nsis
  bump-electron.mjs        the Chromium-CVE "build against latest Electron"
      policy, out of the PS script (5.1 here-string terminator rules)
  README.md

PyInstaller, not the python-embed zip: the frozen meshbay-node.exe is a
genuine relocatable single binary, which is what src/main.js:findNodeBinary
spawns (process.resourcesPath/node-runtime/meshbay-node.exe when packaged) and
what the W3 autostart launcher points at. The embeddable zip needs pip to make
that wrapper and the wrapper bakes in an absolute interpreter path.

build/installer.nsh: on uninstall, taskkill meshbay-node.exe and delete the W3
Startup .vbs (it would point wscript at a deleted binary every sign-in).
%LOCALAPPDATA%\meshbay\ — node.toml, keystore.enc — is never touched.

ffmpeg is not bundled by default (node finds it on PATH); build-win.ps1
-FfmpegDir copies ffmpeg.exe/ffprobe.exe in for a self-contained installer.

Verified on the Windows guest: PyInstaller freeze builds first try
(node-runtime 147 MB), frozen `meshbay-node status` talks to the live daemon's
loopback API; electron-builder --win nsis produces MeshBay-Setup-0.1.0.exe
(155 MB), oneClick/perMachine flags applied, node-runtime bundled at the path
findNodeBinary expects. test_packaging_win.py (14) pins the config invariants
and the NSIS <-> platform.py autostart seam. Node suite 798 pass / 34 skip.

Open: Authenticode signing (13.9 — unsigned => SmartScreen), Windows CI
(18.3), electron-updater. First clean-machine install + DPAPI + autostart
round-trip is a manual check.

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

1 files changed, 45 insertions, 0 deletions

diff --git a/docs/PACKAGING-GUIDE.md b/docs/PACKAGING-GUIDE.md
index 0f9997d..5a5c388 100644
--- a/docs/PACKAGING-GUIDE.md
+++ b/docs/PACKAGING-GUIDE.md
@@ -59,6 +59,51 @@ sudo rpm -e meshbay-client meshbay-hub meshbay-node meshbay-common
 
 ---
 
+## Windows
+
+One installer, **`MeshBay-Setup-<version>.exe`**, carries the client **and** the
+node (with `meshbay-common` inside it). There is no Windows hub.
+
+### Install
+
+Run the installer. It is **per-user** — no administrator prompt — and lands in
+`%LOCALAPPDATA%\Programs\meshbay-client\`. The node daemon ships beside the app
+at `resources\node-runtime\meshbay-node.exe`; the client finds it automatically.
+
+**ffmpeg** is required for video streaming and is *not* in the installer unless
+it was built with `-FfmpegDir`. Otherwise install it separately
+(`winget install ffmpeg`) so the node finds it on `PATH`.
+
+### First run
+
+Open MeshBay and sign in. Use the **Node** page (or a terminal) to provision:
+
+```
+meshbay-node init
+meshbay-node autostart install     # run the daemon at every sign-in (no admin)
+```
+
+Runtime data — `node.toml`, `keystore.enc`, `unlock.key`, `data\` — lives in
+`%LOCALAPPDATA%\meshbay\` and **survives uninstall/reinstall**.
+
+### Uninstall
+
+*Apps & features → MeshBay → Uninstall*, or the Start-menu *Uninstall MeshBay*
+entry. It stops a running daemon and removes the sign-in launcher; it does not
+touch `%LOCALAPPDATA%\meshbay\` (the keystore).
+
+### Build from source
+
+See [`packaging/win/README.md`](../packaging/win/README.md). On a machine with
+Node ≥ 22 and Python ≥ 3.12:
+
+```powershell
+cd packages\meshbay-client
+npm run dist:win
+```
+
+---
+
 ## Post-install: Node (desktop user)
 
 ### 1. Initialize