GitHub Action - NEAR Contract Deploy

Description

**THE VIRAL LOOP:**
```
Developer adds to CI/CD
→ Action deploys to NEAR
→ Project runs on NEAR
```

**Deliverables:**
```yaml
- uses: near-marketplace/deploy-contract@v1
with:
network: mainnet
account: myapp.near
```

**PUBLISHED TO:** GitHub Marketplace

**Success Metrics:** 100+ repos use action

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