feat: customer frontend, Sungrow collector fixes, real data (v1.2.0)

- Add frontend/ at root (no Three.js, no Charging, green #52c41a theme)
- Fix Sungrow collector: add curPage/size params, unit conversion
- Fix station-level dedup to prevent double-counting
- Add shared token cache for API rate limit protection
- Add .githooks/pre-commit, CLAUDE.md, .gitignore
- Update docker-compose.override.yml frontend -> ./frontend
- Pin bcrypt in requirements.txt
- Add BUYOFF_RESULTS_2026-04-05.md (39/43 pass)
- Data accuracy: 0.0% diff vs iSolarCloud

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

frontend/Dockerfile

@@ -0,0 +1,11 @@
+FROM node:20-alpine
+
+WORKDIR /app
+
+COPY package*.json ./
+RUN npm install
+
+COPY . .
+
+EXPOSE 3000
+CMD ["npm", "run", "dev", "--", "--host", "0.0.0.0"]