fix(dashboard): trades pagination + reproducible Docker build

- Add pagination controls to Trades tab (prev/next, offset support)
- Reset page on symbol change
- Use package-lock.json + npm ci for reproducible UI builds

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

dashboard/ui/Dockerfile

@@ -1,7 +1,7 @@
 FROM node:20-alpine AS build
 WORKDIR /app
-COPY package.json .
-RUN npm install
+COPY package.json package-lock.json .
+RUN npm ci
 COPY . .
 RUN npm run build