chore: update default account and add example data

- Update default login email to xinmi@local.com
- Update default password to 12345678 (and bcrypt hash in crm.sql)
- Add example customers, products, and contracts to init SQL
- Fix Docker env interpolation for VITE_API_BASE_URL
- Hardcode local backend API URL in frontend .env files
- Update README and docs to reflect new default credentials

web/Dockerfile

@@ -10,10 +10,6 @@ RUN npm install
 
 COPY . .
 
-# Set the production API URL
-ARG VITE_API_BASE_URL
-ENV VITE_API_BASE_URL=${VITE_API_BASE_URL}
-
 RUN npm run build
 
 FROM nginx:alpine