Initial import: shopdb-flask multi-site asset platform

Flask + Vue rewrite of the classic-ASP shopdb, built as a plugin
framework so sister GE Aerospace sites can adopt it. Product version
0.7.0-pre-0.8.0, plugin contract 0.11.0, 966 backend tests.

Key entry points:
- docs/INSTALL-WINDOWS-IIS.md - tested Windows + IIS install runbook
  (own-site and subpath deployment methods)
- docs/PILOT-DEPLOY.md - production pilot: stand up + import + verify
- docs/IMPORT-API.md - schema-agnostic legacy data import contract
- scripts/site_imports/wjf/ - West Jefferson reference import loader
- docs/adr/ - twelve accepted architecture decision records

Dockerfile

@@ -0,0 +1,80 @@
+# shopdb-flask single-site container.
+#
+# One image, one site. Per ADR-004, each adopting facility runs its own
+# stack with its own DB, secrets, and enabled-plugin list. This image
+# bundles all eleven core plugins (computers, employees, knowledgebase,
+# machines, measuringtools, network, notifications, printers, slides, usb,
+# warranty);
+# install them at runtime with `flask plugin install <name>`.
+#
+# The frontend is built in a first stage and its dist output is copied into
+# the final image so Flask can serve the SPA (register_frontend_routes in
+# shopdb/__init__.py resolves <repo>/frontend/dist).
+#
+# Build:
+#   docker build -t shopdb-flask .
+# Run (with .env):
+#   docker run --env-file .env -p 5001:5001 shopdb-flask
+
+# ---- Stage 1: build the Vue frontend ----
+FROM node:20-slim AS frontendbuild
+
+WORKDIR /build
+
+# Copy only the manifests first so `npm ci` caches on dependency changes.
+COPY frontend/package*.json ./
+RUN npm ci
+
+COPY frontend/ ./
+RUN npm run build
+# Output lands in /build/dist (Vite default), copied into the final stage below.
+
+# ---- Stage 2: Python application image ----
+FROM python:3.12-slim AS base
+
+ENV PYTHONDONTWRITEBYTECODE=1 \
+    PYTHONUNBUFFERED=1 \
+    PIP_NO_CACHE_DIR=1 \
+    PIP_DISABLE_PIP_VERSION_CHECK=1
+
+WORKDIR /app
+
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends \
+        build-essential \
+        default-libmysqlclient-dev \
+        pkg-config \
+        curl \
+    && rm -rf /var/lib/apt/lists/*
+
+COPY requirements.txt ./
+RUN pip install --no-cache-dir -r requirements.txt \
+    && pip install --no-cache-dir gunicorn
+
+COPY shopdb/ ./shopdb/
+COPY plugins/ ./plugins/
+COPY migrations/ ./migrations/
+COPY scripts/ ./scripts/
+COPY wsgi.py ./
+
+# Built SPA from stage 1. Flask serves it via register_frontend_routes.
+COPY --from=frontendbuild /build/dist ./frontend/dist
+
+RUN useradd --create-home --shell /bin/bash shopdb \
+    && chown -R shopdb:shopdb /app
+USER shopdb
+
+EXPOSE 5001
+
+HEALTHCHECK --interval=30s --timeout=5s --start-period=10s --retries=3 \
+    CMD curl --fail --silent http://localhost:5001/api/auth/login -X POST \
+        -H "Content-Type: application/json" -d '{}' \
+        | grep -q "VALIDATION_ERROR" || exit 1
+
+CMD ["gunicorn", \
+     "--bind", "0.0.0.0:5001", \
+     "--workers", "4", \
+     "--timeout", "60", \
+     "--access-logfile", "-", \
+     "--error-logfile", "-", \
+     "wsgi:app"]