List same-named tools of every connector on a server - #1309

Summary

When several connectors on one MCP server expose a tool with the same name, only the first copy was listed and every call went to the first connector. Every DATABASE connector has execute_query, get_database_schema and get_example_queries, so a server with two databases served only one of them (#1296). The same happens with two configs of one catalog provider on one server.

Now:

• The first copy keeps the bare name, so clients that already use it keep working.
• Every other connector's copy is listed with the connector's name as a prefix, e.g. sales_db_execute_query. The name stays within 64 characters and gets a _2 suffix if two connectors have the same name.
• When a name is shared, each description starts with the connector's name, so the model can pick the right one.
• Each registered tool resolves its call in its own connector (connectorIds: [tool.connectorId]), not in the server's whole list. Before, the registry returned the first connector with that name.
• The same connector assigned twice is still skipped and logged, as before.

The executor lookup is unchanged, so the global /mcp endpoint is not affected.

Changes

• planToolSet (mcp-endpoint.controller.ts): dedupe by connector instead of by name, prefix the extra copies, label shared names, scope execution to the tool's connector.
• connectorScopedToolName helper, reusing slugifyForPrefix from the GraphQL built-ins.
• Tests: names of three DATABASE copies, routing of each copy, description labels, unique names when connectors share a name, and the same-connector-twice warning. The fix(mcp): dedupe tool names so a duplicate connector can't 500 the server #313 regression test still checks that a duplicate does not 500.

Type

• Bug fix

Testing

• Added/updated unit tests

Commands, in packages/backend after npm ci and prisma generate:

• npx jest src/mcp-server: 28 suites, 503 tests passed.
• mcp-endpoint.controller.spec.ts with the old controller: 5 of 52 failed (the new tests).
• npx tsc --noEmit -p tsconfig.json: clean.
• npx eslint on the two changed files: clean.

Cloud and self-hosted behave the same. On a server with a single connector per tool name nothing changes.

Checklist

• My code follows the existing code style
• I have tested my changes locally
• This PR has a descriptive title

Related Issues

Fixes #1296