docs: add FXMacroData MCP server example

[roberttidball]

Summary

Adds an FXMacroData MCP server example to the mcpServers tabs in docs/config/tools.md, after the Serply one (#626). Docs only, no code changes.

FXMacroData is a remote MCP server at https://mcp.fxmacrodata.com with official-source macro releases, central bank rates, release calendars and FX rates for 22 currencies. USD releases, the USD calendar and the USD catalogue work without a key; other currencies, FX rates and the rest need a key, sent as Authorization: Bearer <key>.

The example uses a single config with "Authorization": "Bearer ${env:FXMACRODATA_API_KEY}". I checked eca.interpolation/replace-dynamic-strings: an unset ${env:...} with no default resolves to an empty string, and the server treats the empty bearer as keyless, so the same config works with or without a key. Because the Authorization header is configured, initialize-server! skips the OAuth probe, same as the "Static auth header" example.

Validation

I ran the released eca-native-static-linux-amd64 0.161.2 binary as eca server --config-file with the config block extracted verbatim from the new tab, FXMACRODATA_API_KEY unset, and drove initialize/initialized over stdio:

• [MCP] Creating HTTP transport for server 'fxmacrodata' at https://mcp.fxmacrodata.com

• [MCP] Started MCP server fxmacrodata

• tool/serverUpdated reports fxmacrodata as running with 50 tools (data_catalogue, release_calendar, latest_announcements, indicator_query, forex, ...).

• I added a entry in changelog under unreleased section. (Docs-only, like docs: add Serply MCP server example #626, so I left CHANGELOG.md alone. Happy to add a line if you want one.)

• This is not an AI slop.

AI tools helped draft this; I reviewed and tested it. Happy to adjust naming or scope, or drop it if it isn't a direction you want for the docs.

Disclosure: I run FXMacroData.

[ericdallo]

Looks good, thanks!