v0.2.0

docs: rewrite README to reflect updated API surface

Full rewrite of README to match feat/align-mcp-with-api-surface (PR #3):

- Adds discover_traders, get_trader_performance, batch_update_traders
- Groups tools by function (Portfolio / Discovery / Follow Management / Orders)
- Documents CARBONCOPY_BASE_URL env override
- Adds scope-based permissions note
- Updates Features section to mention positions value, unrealised P&L,
  trader discovery, batch operations, and performance analytics
- Links to API_REFERENCE.md in habakkuk for full REST docs