Refresh docs and fix Docker builds for current layout

READMEs: correct the auth model (PocketBase token relay, not JWT/sessions),
document the full feature set (technical checks, fuel, maintenance, documents,
reminders, attachments, integrations, OCPP charging control), the shipping
built-in connectors (toyota, anker-solix), and the current endpoint surface.

Docker: build against the current repo layout — Go 1.26, cmd/server entry
point, Web App source under web/. Add the missing Web App Dockerfile (Go BFF)
and .dockerignore, drop the obsolete AUTH_SECRET, modernise CORS var naming,
and standardise on drivervault-* naming.

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

Web App/Dockerfile

@@ -0,0 +1,51 @@
+# syntax=docker/dockerfile:1
+#
+# Web App image: the Vue SPA is built and embedded into the Go backend-for-
+# frontend (BFF), which serves it and reverse-proxies /api/* to the API Server
+# (API_BASE). This mirrors the production Run-WebApp.ps1 flow, so the browser is
+# always same-origin and all data access still flows through the API Server.
+#
+#   Build context is the "Web App" directory (see Docker/docker-compose.yml).
+
+# --- Stage 1: build the Vue SPA ---------------------------------------------
+FROM node:22-alpine AS web-build
+WORKDIR /web
+COPY web/package.json web/package-lock.json ./
+RUN npm ci
+COPY web/index.html web/vite.config.js ./
+COPY web/src ./src
+COPY web/public ./public
+# Empty -> bundle uses same-origin "/api", which the BFF proxies to API_BASE.
+ARG VITE_API_BASE=""
+ENV VITE_API_BASE=${VITE_API_BASE}
+# vite.config writes to ../server/dist by default; emit into ./dist here so the
+# next stage can embed it.
+RUN npm run build -- --outDir dist --emptyOutDir
+
+# --- Stage 2: build the Go BFF, embedding the SPA ---------------------------
+FROM golang:1.26-alpine AS server-build
+WORKDIR /src
+COPY server/go.mod ./
+# go.sum is optional (stdlib-only module today); copy it if present.
+COPY server/go.su[m] ./
+RUN go mod download
+COPY server/ ./
+# Embed the freshly built SPA (main.go uses //go:embed all:dist).
+COPY --from=web-build /web/dist ./dist
+RUN CGO_ENABLED=0 GOOS=linux go build -trimpath -ldflags="-s -w" -o /out/web-bff .
+
+# --- Runtime stage ----------------------------------------------------------
+FROM alpine:latest
+RUN apk add --no-cache ca-certificates tzdata \
+    && addgroup -S app && adduser -S -G app app
+
+WORKDIR /app
+COPY --from=server-build /out/web-bff /app/web-bff
+
+# Config comes from environment variables (see server/.env.example).
+ENV WEB_ADDR=:8090 \
+    API_BASE=http://api-server:8080
+EXPOSE 8090
+
+USER app
+ENTRYPOINT ["/app/web-bff"]