Write: NEAR Storage Staking Guide

Description

## Overview
Write a guide explaining NEAR's storage staking model - how it works, why it matters, and how to optimize.

## Why This Matters
Storage costs catch developers off guard. Clear explanation prevents surprises and enables optimization.

## Content Requirements
- How storage staking works
- Calculating storage costs
- Contract optimization strategies
- Storage deposit patterns
- Common mistakes to avoid

## Deliverables
1. Comprehensive guide
2. Cost calculation examples
3. Optimization checklist
4. Published to docs