feat(deploy): add the air-gapped Windows installer

Roughly 2500 lines of tested installer had been living in ~/Downloads and an
untracked folder - nothing was under version control.

It goes here rather than in a repo of its own because it depends on application
internals: the `flask plugin` verbs, site-profile.json, MOUNT_PATH, and the
plugin registry. Versioned separately it would drift out of step with the thing
it installs.

Contents: the read-only preflight, the staged installer (bundled MySQL, runtime,
schema, IIS, verify, uninstall), the operator console, the Inno Setup wizard, the
bundle builder and the artwork generator.

bundle/ and Output/ are ignored - regenerable, and ~220MB. plugins.iss is ignored
because build-installer.sh generates it from the staged payload. The artwork IS
committed so a Windows build box does not need Python and cairosvg.

Verified end to end on Windows Server 2025 against a bundled MySQL 8.0 and an
existing MySQL 5.6: fresh install, upgrade with backup and rollback, re-run
idempotency, uninstall, and both deployment methods including switching between
them. Not yet verified: a hypervisor-level air-gapped run, and any load from a
real browser (every HTTP check so far used curl, which sends no Origin header).

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

deploy/windows/installer/build-installer.sh

@@ -0,0 +1,84 @@
+#!/bin/bash
+# Stage a lean per-site bundle next to ShopDBFlask.iss, ready for Inno Setup.
+#
+# The bundle is built FOR ONE SITE from its plugin profile (ADR-013): plugins the
+# site did not choose are absent from the payload entirely. Build one installer
+# per site, not one universal installer.
+#
+# Usage: build-installer.sh <site-profile.json> [repo-path]
+#
+# The wheelhouse cannot be built here. Wheels are cp314 win_amd64 and must be
+# produced ON Windows with the matching Python:
+#   pip download -r requirements.txt -d wheels --only-binary=:all:
+# Copy that wheels\ directory in before compiling.
+set -euo pipefail
+
+HERE="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROFILE="${1:?usage: build-installer.sh <site-profile.json> [repo-path]}"
+REPO="${2:-$HOME/projects/shopdb-flask}"
+BUNDLE="$HERE/bundle"
+
+[ -f "$PROFILE" ] || { echo "profile not found: $PROFILE"; exit 1; }
+[ -d "$REPO" ]    || { echo "repo not found: $REPO"; exit 1; }
+
+echo "==> Staging lean app tree from $PROFILE"
+rm -rf "$BUNDLE/app"
+bash "$REPO/scripts/build-site.sh" "$PROFILE" "$BUNDLE/app"
+
+# build-site.sh emits the SPA as frontend-dist; the installer's web.config and
+# static route expect frontend\dist.
+if [ -d "$BUNDLE/app/frontend-dist" ]; then
+    mkdir -p "$BUNDLE/app/frontend"
+    rm -rf "$BUNDLE/app/frontend/dist"
+    mv "$BUNDLE/app/frontend-dist" "$BUNDLE/app/frontend/dist"
+fi
+# The /shopdb-based build, used when the operator picks the subpath deployment.
+if [ -d "$BUNDLE/app/frontend-dist-subpath" ]; then
+    rm -rf "$BUNDLE/app/frontend/dist-subpath"
+    mv "$BUNDLE/app/frontend-dist-subpath" "$BUNDLE/app/frontend/dist-subpath"
+fi
+
+# Tell the .iss which plugins this bundle actually carries, so the wizard's
+# plugin page always matches the payload instead of a hand-maintained list.
+echo "==> Writing plugins.iss"
+PLUGINS=$(ls "$BUNDLE/app/plugins" 2>/dev/null | tr '\n' ',' | sed 's/,$//')
+# The subpath SPA is built with its base path compiled in, so whether the wizard
+# can OFFER a subpath install is a property of the bundle, not a runtime choice.
+SUBPATH_ALIAS_BUILT=""
+if [ -f "$BUNDLE/app/frontend/dist-subpath/.alias" ]; then
+    SUBPATH_ALIAS_BUILT="$(cat "$BUNDLE/app/frontend/dist-subpath/.alias")"
+fi
+
+cat > "$HERE/plugins.iss" <<EOF
+; GENERATED by build-installer.sh - do not edit.
+; The plugins present in bundle\\app\\plugins at build time.
+#define AvailablePlugins "$PLUGINS"
+; The alias the subpath SPA was built for, or empty if this bundle has no
+; subpath build - in which case the wizard must not offer that option.
+#define SubpathAlias "$SUBPATH_ALIAS_BUILT"
+EOF
+echo "    $PLUGINS"
+
+echo "==> Copying installer scripts"
+mkdir -p "$BUNDLE"
+cp "$HOME/Downloads/shopdb-install.ps1" "$HOME/Downloads/shopdb-preflight.ps1" "$BUNDLE/"
+
+echo ""
+echo "Bundle staged at: $BUNDLE"
+for d in app wheels python httpplatformhandler mysql; do
+    if [ -d "$BUNDLE/$d" ]; then
+        printf '  %-20s %s\n' "$d" "$(du -sh "$BUNDLE/$d" | cut -f1)"
+    else
+        printf '  %-20s MISSING\n' "$d"
+    fi
+done
+echo ""
+echo "  plugins shipped: $(ls "$BUNDLE/app/plugins" 2>/dev/null | tr '\n' ' ')"
+echo ""
+echo "Missing pieces must be added by hand before compiling:"
+echo "  wheels\\              built ON Windows (cp314 win_amd64), ~47 wheels"
+echo "  python\\              python-3.14.6-amd64.exe"
+echo "  httpplatformhandler\\ httpPlatformHandler_amd64.msi"
+echo "  mysql\\               mysql-8.0.46-winx64.msi  (bundled-database option only)"
+echo ""
+echo "Then compile on Windows:  iscc ShopDBFlask.iss"