Orbit/Galaxy MCP: no way to browse or import from Galaxy Data Libraries

A tester asked Orbit to build a history collection from specific samples stored under a shared Galaxy Data Library (Libraries -> ``). Orbit couldn't do it -- there's no MCP tool to browse or import from Data Libraries -- and fell back to "do it in the Web UI."

(The model framed the limitation as a "sandboxed security policy," which is a misattribution; the actual gap is that no MCP endpoint for Data Libraries is exposed.)

This is a galaxy-mcp tool-surface gap; tracking here since that's where testers feel it. One of a small set of "missing Galaxy operation" reports filed together -- see siblings for workflow import, dataset purge, and paired-collection build.

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Filed together as the missing-Galaxy-operation set: #226 (Data Libraries), #227 (workflow import), #228 (dataset purge), #229 (paired-collection build).