feat: add Docker build for Windows NSIS installer via Wine

- contrib/windows/Dockerfile: cross-compile using Wine + xvfb;
  installs Python 3.11 for Windows, builds cli.exe with PyInstaller,
  packages Electron app as NSIS installer
- contrib/windows/build.sh: convenience script to run the Docker build
- frontend/electron/main.cjs: resolve cli.exe on win32, cli on other platforms
- frontend/package.json: add win/nsis target; change extraResources to
  bundle resources/ dir so each platform picks its own binary

contrib/windows/Dockerfile

@@ -0,0 +1,47 @@
+FROM node:22.14.0-bookworm
+
+ENV WINEPREFIX=/root/.wine
+ENV WINEDEBUG=-all
+
+# System dependencies + Wine + Xvfb
+RUN dpkg --add-architecture i386 && \
+    apt-get update && apt-get install -y --no-install-recommends \
+    wine wine64 \
+    python3 python3-pip python3-venv libpython3.11 \
+    binutils wget xvfb ca-certificates \
+    && rm -rf /var/lib/apt/lists/*
+
+WORKDIR /build
+
+# Copy repo
+COPY . .
+
+# Python venv (Linux, for local tools only)
+RUN python3 -m venv venv && \
+    venv/bin/pip install --no-cache-dir -r requirements.txt
+
+# Bootstrap Wine prefix
+RUN wineboot --init 2>/dev/null || true
+
+# Install Python for Windows under Wine (silent, no GUI)
+RUN wget -q "https://www.python.org/ftp/python/3.11.9/python-3.11.9-amd64.exe" -O /tmp/py.exe && \
+    xvfb-run wine /tmp/py.exe /quiet InstallAllUsers=1 PrependPath=1 TargetDir="C:\\Python311" && \
+    rm /tmp/py.exe
+
+# Install Python deps + PyInstaller under Wine Python
+RUN xvfb-run wine "C:\\Python311\\python.exe" -m pip install --no-cache-dir -r requirements.txt pyinstaller
+
+# Compile Python CLI into Windows binary
+RUN xvfb-run wine "C:\\Python311\\python.exe" -m PyInstaller \
+    --onefile --name cli src/cli.py && \
+    mkdir -p frontend/resources && \
+    cp dist/cli.exe frontend/resources/cli.exe
+
+# JS dependencies + electron-builder
+RUN cd frontend && npm ci && npm install --no-save electron-builder
+
+# Build Windows NSIS installer
+RUN cd frontend && npx vite build && npx electron-builder --win nsis --publish never
+
+# Export installer
+CMD cp frontend/release/*.exe /out/

contrib/windows/build.sh

@@ -0,0 +1,18 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+REPO_ROOT=$(cd "$(dirname "$0")/../.." && pwd)
+OUT_DIR="$REPO_ROOT/release"
+
+mkdir -p "$OUT_DIR"
+
+docker build -t wallet-gen-builder-win \
+    -f "$REPO_ROOT/contrib/windows/Dockerfile" \
+    "$REPO_ROOT"
+
+docker run --rm \
+    -v "$OUT_DIR:/out" \
+    wallet-gen-builder-win
+
+echo "Installer saved to: $OUT_DIR"
+ls "$OUT_DIR"/*.exe