Add meeting participant removal controls

## Feature request

Add support for removing a participant from an active meeting through Conclave.

## Motivation

During the meeting, a participant asked Conclave to remove another attendee. Conclave currently cannot perform this action and directs the host to use the meeting platform controls.

## Proposed behavior

- Allow authorized meeting roles (for example, host/co-host) to ask Conclave to remove a named participant.
- Require an explicit confirmation step before the removal is executed.
- Reject requests from unauthorized participants.
- Return a clear success or failure message after the action.

## Acceptance criteria

- [ ] Conclave can identify the requested participant from the active meeting roster.
- [ ] Authorization is checked before any removal action is offered.
- [ ] A confirmation is required immediately before removal.
- [ ] The removal is performed through the meeting platform integration when authorized and confirmed.
- [ ] Errors such as ambiguous names, insufficient permissions, or integration failures are handled clearly.

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Requested by **Ishaan** during a Conclave meeting.

The issue names no files, tests, or entry points. Start by tracing the active-meeting roster and meeting-platform integration, then identify where role authorization and confirmation belong. Done means authorized hosts or co-hosts can confirm removal of an unambiguous participant, while unauthorized, ambiguous, and integration-failure cases return clear errors.

Written by the indexing model from the issue text.