v2.0 - JSON-RPC adapter, server refactor, bug fixes

- Add JSON-RPC adapter for local/hosted Ethereum nodes (530 lines)
- Extract server.ts from index.ts (clean separation of transport and logic)
- Fix formatUSD crashes on null/undefined/string/array values from external APIs
- Fix get_protocol_info crash (data.tvl is an array, not a number)
- Fix get_global_defi crash (CoinGecko returns strings for ratio/dominance)
- Fix smart_get_price/smart_get_eth_price crash on null change24h
- Fix get_top_tokens crash on null change24h
- Harden all growthepie L2 metric handlers against null values
- Remove MCP app tools (gas-status, price-chart, etc.) for future reintroduction
- Remove Cloudflare worker, Vite, and wrangler configs
- Strip vite/wrangler/@cloudflare devDeps
- Add JSON-RPC test suite (input validation + 15 API tests)
- Update .gitignore