fix(teams): search Group Chats by name

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Summary

The Group Chat picker sent a Group Chat request to user search. The picker now opens Group Chat name under Microsoft Teams > Find a Group Chat.

The picker searches partial and full chat titles. It never uses a participant name as the query.

The Graph client reads tenant user IDs, then reads each user's chat metadata through supported application endpoints. It filters Group Chats, validates canonical IDs, deduplicates results, and follows user and chat pages.

The search uses bounded request batches and opaque five-minute cursors. The TUI offers Continue search when metadata remains. It reports partial coverage when a user chat list is unavailable.

The change needs User.Read.All and optional Chat.ReadBasic.All. It does not grant consent, read chat messages, change principal grants, or relax ingress policy.

Validation

• Focused Teams CLI tests: 162 passed.
• Full CLI suite: 1,536 passed.
• Native config-teams smoke tape: passed.
• Strict OpenSpec validation: passed.
• Slopwatch and copyright-header checks: passed.
• git diff --check: passed.
• The full formatter reports pre-existing whitespace errors outside this change.
• Behavioral evals need model-provider values. The local run stopped before Docker or a model call.

Limits

This PR does not access a Teams tenant or change Entra consent. Live deployment validation remains with the owner.