* feat(microsoft_365_copilot): add Microsoft 365 Copilot chat provider with OAuth token exchange
* fix(ui): create a credential for credential-only auth types in Add Model
* fix(microsoft_365_copilot): accept max_tokens and list the chat model
* fix(microsoft_365_copilot): register provider model set
* fix(ui): hide other auth types' fields when credential-only types are filtered
* fix(health): do not inherit stored auth settings when a connection test brings its own api_key
* docs(health): restore connection-test inheritance docstrings
* fix(lint): suppress justified provider boundary casts
* fix(lint): satisfy M365 type-discipline gate
* fix(types): eliminate type-check gate regressions
* style: shorten suppression reasons so ruff format leaves them on one line
* refactor(types): drop shared-file type widening unrelated to the Copilot provider
* fix(health): pass caller headers as secret_fields to connection-test probes
* fix(types): type connection-test probe and token counter locally
* fix(lint): drop cast import from connection-test header getter
* chore: remove explanatory comments flagged by review
* fix(proxy): gate OAuth client credentials behind proxy admin
* fix(router): skip cooldown on caller-scoped OAuth auth failures
* fix(router): skip fallback cooldown on caller-scoped OAuth auth failures
* fix(router): type caller-scoped cooldown lookups
* fix(ci): include Microsoft 365 Copilot tests in unit shard
* fix(proxy): keep saved endpoint when test_connection retests a deployment by id
* fix(m365): collapse doubled Graph replies
* fix(m365): preserve trailing system messages
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Co-authored-by: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>