docs: add index composition and portfolios to the cloud table, refresh tool counts

[daniel3303]

The cloud MCP server now exposes portfolio tools, and the cloud carries index composition data, but the README's What's Included table and tool counts predate both.

What changed

• Two new cloud-only rows: Index Composition (constituents plus membership history for the S&P 500/400/600, Nasdaq-100, Russell 1000/2000 and the Dow, plus rule-based add/delete forecasts) and Portfolios (holdings and watchlists across stocks and options, cost basis, realized/unrealized P&L, the only write tools on the server).
• A rationale bullet for each under Why Some Data Is Cloud-Only, so every cloud-only row is still covered there. Portfolios is deliberately not framed as an infrastructure problem: it is per-account state, and the self-hosted build has no accounts.
• Tool counts refreshed in all three places they appear: hosted is 108, self-hosted stays 64, so the cloud adds 44 rather than 33.

Counts

Verified two ways: distinct [McpServerTool(Name = ...)] names across the modules each host registers (64 OSS + 42 commercial modules + 2 feedback tools = 108), and the live tool list of https://mcp.equibles.com/mcp (108).

Note: index data has no MCP tools yet, so it contributes nothing to the counts. It is a data-domain row like Earnings Call Audio.