Деплой: PowerShell-версия build-push (на Windows bash уходит в WSL и падает)

- scripts/build-push.ps1: arm64 buildx bake + push, аналог build-push.sh для Windows-дева (ASCII).
- deploy/pi/README: указать .ps1 для Windows и почему `bash ...` в PowerShell не работает.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

scripts/build-push.ps1

@@ -0,0 +1,26 @@
+# Build prod images (app + tunnel) for linux/arm64 (Raspberry Pi) and push to the registry.
+# Run on the DEV machine with Docker Desktop / buildx. Registry and tag come from the root
+# .env (IMAGE_REGISTRY / IMAGE_TAG) - the same values docker-compose.yml uses.
+# Log in to the registry once before running:  docker login gitea.arseniev.info
+# Keep this file ASCII-only (Windows PowerShell 5.1 mangles non-ASCII without a BOM).
+$ErrorActionPreference = "Stop"
+$root = Split-Path -Parent $PSScriptRoot
+Set-Location $root
+
+# Builder with multi-arch push support (docker-container driver) - create if missing.
+docker buildx inspect fsbuilder *> $null
+if ($LASTEXITCODE -ne 0) {
+    docker buildx create --name fsbuilder --driver docker-container | Out-Null
+}
+
+# arm64 emulation on an x86 host (usually already present in Docker Desktop; idempotent).
+docker run --privileged --rm tonistiigi/binfmt --install arm64 | Out-Null
+
+Write-Host "Building app+tunnel for linux/arm64 and pushing to the registry..." -ForegroundColor Green
+docker buildx bake -f docker-compose.yml --builder fsbuilder --set "*.platform=linux/arm64" --push
+if ($LASTEXITCODE -ne 0) {
+    Write-Host "Build/push FAILED (exit $LASTEXITCODE)." -ForegroundColor Red
+    exit 1
+}
+
+Write-Host "Done. On the Pi:  docker compose pull && docker compose up -d" -ForegroundColor Green