Expose MaintainerTeam as part of the GetFlag response

[asabherwal-design]

Summary

The get-flag tool in the LaunchDarkly Feature Management MCP returns a maintainer field scoped to individual user maintainers, but does not expose maintainerTeamKey. This makes it impossible to filter flags
by their owning team programmatically through the MCP.

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Problem Statement

When a feature flag is maintained by a team (rather than an individual user), the MCP's get-flag response returns "maintainer": null even though the flag has a team maintainer set in LaunchDarkly. The
maintainerTeamKey field — available in the LD REST API (GET /api/v2/flags/{projectKey}/{flagKey}) — is silently dropped from the MCP response.

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Proposed Solution

Include maintainerTeamKey (and optionally maintainerTeam.name) in the get-flag tool response alongside the existing maintainer field. The LD REST API already returns this data — it just needs to be mapped
through.

Desired response shape:
{
"key": "my-flag",
"maintainer": null,
"maintainerTeamKey": "team-name",
"maintainerTeam": {
"key": "team",
"name": "Team Name"
}
}

Ideally list-flags would also support a maintainerTeamKey filter parameter so callers can retrieve all flags for a team without post-filtering client-side.

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