symfony/mcp-bundle 0.12 requires mcp/sdk ^0.7 and 0.13 requires ^0.8.1,
so the two move together. 0.13 serves several named servers, which
changes the wiring: mcp.registry is gone, each server gets its own
mcp.server.<name>.registry, and the configuration moved under
mcp.servers.<name> with the HTTP path defaulting to /mcp/<name>.

The registry can no longer be decorated from configuration, since the
ids are dynamic and there may be more than one. McpRegistryPass finds
every server through its builder tag and decorates each registry, which
is also what makes the decoration keep working for a multi-server setup.

The fixture pins the path back to /mcp so the functional tests keep
their URL, and declares the mandatory registry node as "*"; that node
only drives the bundle's own attribute discovery, and API Platform
supplies its elements through the mcp.loader tag instead.

The mcp.loader and mcp.request_handler tags are unchanged and still
reach every server, so the loader, the state handlers and the event
handlers need no adaptation.