Adds optional-mcps/blender (ahujasid/blender-mcp, stdio via uvx). The
server advertises 22 tools; 18 front optional asset services with no
upstream trim mechanism, so tools.default_enabled pins the install to
the core surface (scene/object info, viewport screenshot, code exec)
and the rest stay opt-in through 'hermes mcp configure blender'.
Manifests can now declare transport.env (static, non-secret subprocess
env vars), parsed/validated in _parse_manifest and written by
_build_server_config — used here to ship DISABLE_TELEMETRY=true per
the no-telemetry-without-opt-in policy. Runtime already honored
per-server env; manifests just couldn't declare it.
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